What have you listened to other than the Apple Earbuds? I can imagine that there are people who won't like the Z5, but for the most part it's not as terrible as you describe it.
Maybe the LH Verb are more your style

Anyway, joking aside, here are FR and CSD from SEEKO:


There is some midrange bleed, but not that much. Ringing in the treble is minimal compared to many other BA models.
It's possible you got a poor fit with them. Dunno.
Perhaps you merely feel the bass is too boosted, and it does have a lot of bass. Then again, so do many "high-end" flagship IEMs these days.