> Not sure what you mean by "user"

GPTel is on the user side of transient.  Karthink or another contributor wrote GPTel to use transient that way.  Perhaps they need to create new suffixes dynamically, but even that can be done with `define-suffix' etc.  If someone calls `define-suffix' with a really long name, there's nothing transient can or should do about it.

Actually, I recommend taking this to GPTel.  You can ping me on their Github @psionic-k and I'll help Karthink or others consider an alternative approach that has sensible symbol names.

> is highly likely to appear in the extremely long tail of the enormous symbol

True, but the symbols in question contain "transient:" and ":--" strings that should be easy to filter out.  Lots of completion packages can filter those.