Works on a focus but when used on a scroll or slate, returns "Scribe's Gambit: needs a place that will accept 'pattern' in other hand but got 'scroll/slate'. Tested in fabric version 1.19.2-0.10.3.

I'm testing this in the same version of the mod, but I can't reproduce this. Which pattern/s failed for you?

I tried with a few different ones, with and without the "parentheses" hexes. I thought I read something about it not working with mind's reflection but would there be other restrictions or things I could be doing wrong?

Were you writing to an already written slate/scroll? And were you writing a list of patterns, or the pattern itself?

You should be using Consideration, not Introspection/Retrospection. Go Introspection, <the pattern you want>, Scribe's Gambit