I would'nt give a game that could not be rendered correctly on a 64x64 display 5 stars for authenticity. Its not 100% 64x64 then.
However according to the FAQ
"Can I use screen effects like CRT or scanlines that may exceed the actual 64x64 limit? YES! But, make sure it's optional and that the game itself is 64x64 before effects."
So if the bloom is a screen effect and not something thats applied on a per object basis it might be within the rules. If you're dead set on using them I suggest having them off by default. Perhaps try getting in touch with one of the hosts on discord.
I mean, I would hope that the post processing happens before the pixel perfect stuff so that it actually appears like it should on a 64x64 screen, but im not too sure as I havent added it yet. If it doesnt get pixelated, i will add it as an optional effect thats off by default though since i do want that option of having the additional flair as it fits with the game concept im going after
