Actually I just looked at the code for the mod I mentioned (
https://vborg.vbsupport.ru/showthread.php?t=264858) and I see that what I actually did was to disable ajax for quick reply if the mod is enabled, so I suppose I couldn't figure out any other way for it to work. But I also was trying to make a mod without code changes, so if you only want to get it to work on your site you always have the option of modifying the code.