we have tried to implement custom TikTok pixel in GTM with the base Pixel code in the custom HTML tag and custom events implemented with each cHTML tag as well 
Tags are firing properly, and Pixel Helper extension also shows us events 
Test events section inside TikTok Ad manager records that events 
I have tried to send standard AddToWishlist event with cHTML also, and it was recorded without errors in Test events section, you can see below on the last image.
The problem is we can't find all custom events in Assets overview reporting although there are successful page views sent by the pixel. Why can't we observe those events in Overview? Official TikTok docs tell that is possible to send custom events with the custom code now
After contacting TikTok support and showing them screens of this set up they just turned on all custom events in our analytics and we could see the events in our Ad manager. So the set up is correct, the problem was on TikTok reporting side.