Hmm, interesting. I can see why you might want to count the event as a character, since it's technically something else that has to execute after the string is completed. The </w> itself probably shouldn't count as a character, but as you said, it was a workaround anyway.
Actually, another workaround would probably be to just omit the </w>, because it's unnecessary if the string is ending there anyway. I'll do that manually on my end (this situation only occurs once); not sure if this would be doable within STM itself. But yeah, event execution can be finnicky, and that does sound like it would be a hard change to make without testing some things first.