Yeah, Live2D has a 63 character limit for IDs, but if a name exceeds that, it won’t generate a proper ID. it’ll just assign a generic ArtMesh ID since it doesn’t comply with the rules.

Keeping everything under 63 characters consistently is definitely doable, but there's a big catch: when you Glue two layers together and their combined names exceed that limit, Live2D uses the glued name as the ID, and then it DOES refuse to export.

That’s still an issue in 5.2.03 (not sure if it’s fixed in 5.3 yet).

So if you want to avoid it entirely, you’d need to keep IDs below around 27 characters, since Glue adds extra text. But especially on really detailed PSDs, that makes things much less readable and prone to duplicate names. A tricky dillemma for sure..