Yeah, like i said, i just kinda threw the saltire in there and this timeline diverges in the middle ages so no ustasa and no controversial background to the symbolUsing Ustaša-inspired symbolism has very strong connotations to say the least, so I would keep that in mind when making flags. If it is just going to be a Croatian knot though, that will probably work fine, as the positioning and coloration are different enough that people won't likely see the similarities.. I personally would go with 2 for Croatia, and you don't always have to be super alternate. I would go with 1 for Poland.
The blue means Russia basically, It is based off of the Russian Naval Ensign, so it would, IMHO, be unlikely to be used by polish people independent from Tsarist or Republican Russian rule.
Edit: yeah, the symbol is intended, in this timeline, to represent solely a croatian knot, ITTL, the symbol is as harmless as a celtic cross