Anecdotic vs. Anecdotal… sometimes synonyms, but fairly non-exchangeable?

I’m a bit puzzled by these two words' meaning. Observing examples and the use in context it looks like anecdotal is preferred to be used as an adjective with collocations such as: “anecdotal evidence”, “anecdotal accounts" and similar expressions.

Anecdotic seems to be more like an abstract quality term, more used when you refer to stories, scenes, facts and the way some people tell experiences. I’ve also noticed some collocations like to be “of the anecdotic kind”.

But maybe there’s more to it than I have grasped from what I’ve read. (?) And sometimes they could be used interchangeably, but it’s not easy to figure out when for me (I’m a non-native speaker BTW).

You seem to grasp the basic meanings. As a native speaker, I would just say that "anecdotic" is rather uncommon (I had to look it up) and you might consider avoiding it.