There are several localization issues in files for Russian language.
Here they are (right translation are there below):
languagecore_f.pbo:
<Key
ID="str_a3_cfgdebriefing_deserter_0"> <Original>Missing in action</Original> <English>Missing in action</English> <Russian>Missing in action</Russian>
</Key>
Missing in action = Пропал без вести
<Key
ID="str_a3_cfguicolors_gui_presets_presetalpha_0"> <Original>Arma 3 Alpha</Original> <English>Arma 3 Alpha</English> <Russian>Arma 3 - альфа-версия</Russian>
</Key>
Arma 3 - альфа-версия = Альфа-версия Arma 3
<Key
ID="str_a3_cfguigrids_igui_0"> <Original>HUD</Original> <English>HUD</English> <Russian>HUD</Russian>
</Key>
HUD = ИЛС (It means "Индикатор на Лобовом Стекле", short abbreviation ИЛС)
<Key
ID="str_a3_cfgmarkers_nato_uav"> <Original>UAV</Original> <English>UAV</English> <Russian>БПА</Russian>
</Key>
UAV = БПЛА (not БПА)
<Key
ID="str_a3_cfgnotifications_tridentfriendly_0"> <Original>DIPLOMACY UPDATE</Original> <English>DIPLOMACY UPDATE</English> <Russian>ДИПЛОМАТИЧЕСКОГО СТАТУС</Russian>
</Key>
DIPLOMACY UPDATE = ДИПЛОМАТИЧЕСКИЙ СТАТУС (not ДИПЛОМАТИЧЕСКОГО СТАТУС)
<Key
ID="str_a3_cfgnotifications_briefingwarninghub_1"> <Original>The operational briefing begins in %1:%2.</Original> <English>The operational briefing begins in %1:%2.</English> <Russian>The operational briefing begins in %1:%2.</Russian>
</Key>
The operational briefing begins in %1:%2. = Инструктаж по операции начнется через %1 ч. %2 мин.
<Key
ID="str_a3_cfgnotifications_exfilcommencing_0"> <Original>COMMENCING OPERATION</Original> <English>COMMENCING OPERATION</English> <Russian>COMMENCING OPERATION</Russian>
</Key>
COMMENCING OPERATION = НАЧАЛО ОПЕРАЦИИ (or ОПЕРАЦИЯ НАЧИНАЕТСЯ)
<Key
ID="str_a3_cfgnotifications_exfilnotification_0"> <Original>ASSEMBLE</Original> <English>ASSEMBLE</English> <Russian>ASSEMBLE</Russian>
</Key>
ASSEMBLE = СБОР (or СОБРАТЬСЯ)
<Key
ID="str_a3_cfgnotifications_exfilnotification_1"> <Original>The operation begins in %1:%2.</Original> <English>The operation begins in %1:%2.</English> <Russian>The operation begins in %1:%2.</Russian>
</Key>
The operation begins in %1:%2. = Операция начнется через %1 ч. %2 мин.
<Key
ID="str_a3_cfgmpgametypes_tdm_shortcut"> <Original>TDM</Original> <English>TDM</English> <Russian>К. бой</Russian>
</Key>
TDM = Ком. бой (not K. бой)
<Key
ID="str_a3_rscdisplaygameoptions_textadaptivecrosshair"> <Original>Adaptive Crosshair:</Original> <English>Adaptive Crosshair:</English> <Russian>Adaptive Crosshair:</Russian>
</Key>
Adaptive Crosshair: = Адаптивный прицел:
<Key
ID="str_a3_rscdisplaymicsensitivityoptions_textprogressval"> <Original>100%</Original> <English>100%</English> <Russian>1</Russian>
</Key>
100% = 100% (not 1, or maybe there is something I don't know :)
<Key
ID="str_a3_rscuavuav_items_uavwatch0"> <Original>Switch to UAV Camera</Original> <English>Switch to UAV Camera</English> <Russian>Камера БПА</Russian>
</Key>
<Key
ID="str_a3_rscuavuav_items_uavgunner0"> <Original>Switch to UAV Gunner</Original> <English>Switch to UAV Gunner</English> <Russian>Стрелок БПА</Russian>
</Key>
<Key
ID="str_a3_rscuavuav_items_uavdriver0"> <Original>Switch to UAV Driver</Original> <English>Switch to UAV Driver</English> <Russian>Оператор БПА</Russian>
</Key>
<Key
ID="str_a3_rscuavuav0"> <Original>UAV</Original> <English>UAV</English> <Russian>БПА</Russian>
</Key>
БПА = БПЛА
<Key
ID="str_a3_copilot"> <Original>Copilot</Original> <English>Copilot</English> <Russian>Copilot</Russian>
</Key>
Copilot = 2-й пилот
<Key
ID="str_a3_left_gunner"> <Original>Left door gunner</Original> <English>Left door gunner</English> <Russian>Left door gunner</Russian>
</Key>
Left door gunner = Стрелок левой двери
<Key
ID="str_a3_rear_gunner"> <Original>Rear gunner</Original> <English>Rear gunner</English> <Russian>Rear gunner</Russian>
</Key>
Rear gunner = Задний стрелок
<Key
ID="str_a3_right_gunner"> <Original>Right door gunner</Original> <English>Right door gunner</English> <Russian>Right door gunner</Russian>
</Key>
Right door gunner = Стрелок правой двери
<Key
ID="STR_STEAM_FILE_DOWNLOAD_DISK_FULL"> <Original>Disk is full. Downloading of the steam file has failed.</Original> <English>Disk is full. Downloading of the steam file has failed.</English> <Russian>Disk is full. Downloading of the steam file has failed.</Russian>
</Key>
Disk is full. Downloading of the steam file has failed. = Нет места на диске. Загрузка файла не удалась.
<Key
ID="STR_WORKSHOP_SORT_ADDED"> <Original>Sort by time added</Original> <English>Sort by time added</English> <Russian>Sort by time added</Russian>
</Key>
Sort by time added = Сорт. по времени добавл.
<Key
ID="STR_WORKSHOP_SORT_NAME"> <Original>Sort by name</Original> <English>Sort by name</English> <Russian>Sort by name</Russian>
</Key>
Sort by name = Сорт. по имени
<Key
ID="STR_WORKSHOP_SORT_RATING"> <Original>Sort by rating</Original> <English>Sort by rating</English> <Russian>Sort by rating</Russian>
</Key>
Sort by rating = Сорт. по рейтингу
<Key
ID="str_a3_rschcmainmenu_items_uav0"> <Original>UAV</Original> <English>UAV</English> <Russian>БПА</Russian>
</Key>
<Key
ID="str_a3_rschcuav0"> <Original>UAV</Original> <English>UAV</English> <Russian>БПА</Russian>
</Key>
<Key
ID="str_a3_rschcuav_items_uavdriver0">
<Original>Switch to UAV Driver</Original>
<English>Switch to UAV Driver</English>
<Russian>Переключиться на оператора БПА</Russian>
</Key>
<Key
ID="str_a3_rschcuav_items_uavgunner0">
<Original>Switch to UAV Gunner</Original>
<English>Switch to UAV Gunner</English>
<Russian>Переключиться на стрелка БПА</Russian>
</Key>
<Key
ID="str_a3_rschcuav_items_uavwatch0">
<Original>Switch to UAV Camera</Original>
<English>Switch to UAV Camera</English>
<Russian>Переключиться на камеру БПА</Russian>
</Key>БПА everywhere to БПЛА
<Key
ID="str_disp_arcgrp_units_list"> <Original>List of units in the group</Original> <English>List of units in the group</English> <Russian>List of units in the group</Russian>
</Key>
List of units in the group = Список боевых единиц в группе
<Key
ID="str_q_west"> <Original>West</Original> <English>West</English> <Russian>Синие</Russian>
</Key>
West = Запад (not Синие, it means movement or sight directon)
----------------------------------------------------------------
language_f.pbo:
Incorrect paths to game resources, e.g.:
<Key
ID="str_a3_vehicguided0">
<Original>Guided missiles are only useful when a target is locked. As a gunner, point at the target and press %11 to lock the target. Normal targets have a square sign <img size='1' %5 image='A3\UI_F\data\IGUI\Cfg\Cursors\known_target_ca.paa' />, the locked target has an additional diamond mark <img size='1' %5 image='A3\UI_F\data\IGUI\Cfg\Cursors\lock_target_ca.paa' />. To switch to the next target, press %12.</Original>
<English>Guided missiles are only useful when a target is locked. As a gunner, point at the target and press %11 to lock the target. Normal targets have a square sign <img size='1' %5 image='A3\UI_F\data\IGUI\Cfg\Cursors\known_target_ca.paa' />, the locked target has an additional diamond mark <img size='1' %5 image='A3\UI_F\data\IGUI\Cfg\Cursors\lock_target_ca.paa' />. To switch to the next target, press %12.</English>
<Russian>Самонаводящиеся ракеты можно использовать только в том случае, если цель захвачена в прицел. Нажмите %11 чтобы захватить цель. Обычные цели обозначены квадратными значками <img size='1' %5 image='A3\data\IGUI\Cfg\Cursors\known_target_ca.paa' />, у захваченной цели есть дополнительный ромбический значок <img size='1' %5 image='A3\data\IGUI\Cfg\Cursors\lock_target_ca.paa' />. Чтобы переключиться на другую цель снова нажмите %11.</Russian>
</Key>A3\UI_F\data\IGUI\ for Original and English language, A3\data\IGUI\Cfg\ for Russian, it should be A3\UI_F\data\ everywhere