Death is very slow and expensive. Beyond the earlygame it typically takes two full turns to land Death. (Originally it was 18 CT, and always took two full turns to land). 48 MP makes it like...the most expensive status spell in the game, and not far below casting Holy on someone. I don't know when it got upped to 180 hit-rate, though (last I checked it was 160) but certainly it has accuracy issues where something like Holy does not.
Frog...the thing about Frog is that we want to be careful about stepping on Oracle's toes. Oracle has a very similar spell to Frog in Petrify. In fact, Frog is less CT, less MP, and less JP than Petrify. It's also slightly less accurate now that Petrify is buffed to 130; I'd be fine with matching that accuracy.
One thing that makes Frog cool, though, is that you can cast it if you're turned into a frog (and use it to un-frog yourself). Which means, if you have a master Wizard, you're going to want to know Frog, just on the off chance that this Wizard gets turned into a Frog, or needs to de-Frog an ally.
It's also just a contrast thing, though. Death is slow and expensive and long range and accurate. Frog is fast, cheap, short range, and inaccurate. If we want to push Frog a little harder, my inclination would be to emphasize these traits rather than make it more like Death. For instance...100 JP, 9 MP, 4 CT. Or alternatively, raise the accuracy, but lower the range to 1 to make it like a D&D touch spell. It's possible that kind of change would make Black Magic Calc more powerful than we want, though.
But...yeah, it's less of an issue of "we don't know how to make this spell competitive with Death" and more of an issue of "How do we do so without trampling all over Yin Yang Magic's niche?"
