Is your feature request related to a problem? Please describe.
If i make a typo when inputting a spell id into various fields, then the field just goes blank if the value WeakAuras gets doesn't correspond to a spell it knows. It would be nice if instead WeakAuras showed something like 123456 (|cffffff00Unknown Spell|r), so I at least get confirmation that the input was accepted, even if it was nonsense.

i think aceconfig accepts validate field on the option table? that produces a static popup IIRC. maybe that would be "good enough".

I don't see a way on how to implement that though, that is without storing the invalid spell id into the aura.

without storing the invalid spell id into the aura

well yeah, that's what I thought WA did if you gave it garbage. But on closer look, no I'm just being silly.

Still, though, maybe WeakAuras should just complain but still accept garbage. Like, isn't this exactly the scenario WeakAuras finds itself in if you imported an aura meant for TWW into SoD?

yeah if it's a number we can store it easily. I wouldn't store arbitary string though.