As mentioned in T158257, since the HeadTorch item was swapped from the Headgear inventoryslot to Eyewear, it is no longer possible to let infected wear headtorches, which is disappointing for servers that have been doing that ever since it was made possible.

I noted that the mod PvZMod Customisable zombies has enabled the Eyewear slot for infected - but when infected wear headtorches in that slot it doesn't work fully. You can see the headtorch on their heads, but there will be no illumination. However, by editing the headtorch config to allow it to also go into the Headgear slot, it will work as before.

So, it would be nice if the feature was made functional again. Either by enabling the Eyewear slot for infected and configuring it so it works with headtorches like the Headgear slot does, or by simply allowing the headtorch to be put in either slot which would let the previous configuration work as before.