I haven't had any problems with TalkBoxForPlayers. The only thing I can say is that the game version should be 3.1. The player ID is not counted as 1, 2, 3, 4, 5, 6, 7, 8, but as 1, 2, 4, 8, 16, 32, 64, 128, and the two arguments: IconTooltipRef and AddTextRef should only contain quotes without a link "", as the link text is not displayed anyway (a bug, etc.). You can see examples of TalkBoxForPlayers working stably on my map "White Temple". And yes, I recommend editing the .lua code only in the HoMM5MapScriptsEditor program.
I just checked the map in online mode. The first time it worked normally, but the second time it crashed. Hmm.
I am testing it in hot-seat mode (because I can't run two clients on one PC), and I haven't noticed any crashes, and the saves seem to be working fine. But I'm afraid to continue working, as if I'm sitting on a powder keg. I will take a look at your map, thank you.
Будь яростней пред ночью всех ночей,
Не дай погаснуть свету своему!
Хоть мудрый знает – не осилишь тьму
Во мгле словами не зажжёшь лучей –
Не уходи безропотно во тьму.