Ah ok, so it’s really a question of “is it ok to mix styles of trailing vs non-trailing commas” since if the formatter doesn’t enforce it, it’s going to happen/credo rule will be needed (as touched on above). I know that non-trailing was chosen due to the reasons @lud mentioned (José has mentioned this before and I had assumed that post was in the linked thread but I only read the first few posts).
For me the lack of trailing commas doesn’t bother me because I pretty much always put a new line whenever there is a comma separating any other than simple tokens, even it can easily fit on one line. In fact the HEEx formatter drives me nuts in that it will for someone onto one line if it’s possible to do so (I realize this comes from Prettier). When it comes to diffs, this is way way waaaaaaaaaay more infuriating than what non-trailing commas gives you.
Sorting is the bigger issue for sure, but editors should be able to solve fairly easily, especially if they support treesitter. And I suppose nowadays you can just highlight some text and say “Computer, please sort this list and reblance the commas, thx.”
want to switch to proper LSP config but too lazy) with 
I like that my editor mostly gets indentation right. There are a still a few annoying things.
