I was too busy using Sanae for support to test her offense cards. (How long are we going to keep spoilering all the characters, is it really still necessary) In this game, Miracle Fruit is soooooo much better than the previous, and her heal is easier to use as well. Sanae's offense is perfectly suitable for randoms if you're so inclined just like every other character since you can switch boosted stats (although buffing up a slightly slower partner with Fruits is still perfectly viable in randoms so you don't have to buildswitch) but I doubt it's good enough to seriously consider on bosses over investing in her defenses. Maybe if the boss was weak to SPI? She's more important for supporting the team in bossfights... but you could maybe pull a good offensive Sanae against a SPI-weak boss.
Also, the enhancer skill increases a buff by 16% of it's original value multiplicatively, it doesn't add 16% on. Yeah, kind of disappointing. I'm not sure whether or not it effects that, because the difference wasn't large enough for me to have it as a high priority skill. The buffing heals are the best thing about the class, followed by healing buffs- although being able to slap an offense buff on anyone isn't half bad either. But when you have the points for it, yeah, it's still considerable to eke just a bit more oomph from your buffs.