Small update after 1.1 update.
Even though update changelog states that replication was fixed, its actually not.
I used {EEF8495A9A6787A6}Prefabs/Weapons/Core/Ammo_MortarShell_Base.et as base for my projectile, still nothing, player on island few KMs away from everon airfield was damaged but no particle/sound played for him.

In T176362#2518651, @Geez wrote:

Hello Tactical_Toxic.
This is not broken, just requires an additional thing setup to work.

From: https://reforger.armaplatform.com/news/mod-report-2

Show Hitzones Debug
From now on, if you want to use "Show hit zones" debug located in GameCode->Hit Zones you will need to enable the debug of HandleDamageSystem. You can do it from the diag menu like this: Systems-> Systems Diag -> Frame -> Check HandleDamageSystem
Pin

Awesome!

Small update to ticket, based on BI_petanjek answer.