ew rom or flash an older one. Basically, Celio will get these curve balls pitched from different phones. Whatever the bluetooth problem is/was, it was pervasive occurring through several different roms and phones, ah most likely from the ce core in my opinion, though I'm not a programmer.
But check out the celio 1.4.0.93 beta firmware & software updates (you'll likely want to anyway). If you don't want to flash roms--then likely if this last celio update doesn't take care of the problem, (reacting to the change in the windows mobile /ce core in the way that windows moile handles bluetooth) the a subsequent update will do so.
What I'm trying to say is that the bluetooth not recognizing was not something celio did/changed but rather something that microsoft did/changed in some of the later roms. But the celio programmers are very agressive I've noticed and so if the last update didn't fix it, subsequent ones likely will. x7510 support/software is still in bet after all.