The bottom text box of a flip card doesn't show what you've typed in it while you're editing the card, although it's there when you save changes. If you preview changes, it actually clears the enter bottom half. You also can't set the frame color for the top half separately from the mana cost, although that works for the bottom half, even though I'd expect the bottom to use the same frame as the top by default.

I'm on a very out-of-date version of Firefox, if that matters.

I fixed the issue with preview changes losing the second half multipart cards! It was about two characters in the wrong place :)

The editing boxes for flip cards work for me on Chrome, but their positions are pretty dodgily located; I'm not that surprised they go wrong on an old Firefox.

But yes, you're right, if anyone wanted to make a flip card with mana costs and but halves actually coloured black and white, they couldn't do it. Well, they could, actually, but they'd have to use the double-faced card form to do it, and then switch to the flip form after setting those nonstandard frames.

I'm... inclined to treat this as mostly fixed? There is still an edge case that's not easy to do since you can't use the flip card form to do it, so I'll leave half of this red, but the bottom half :)