Couldn't it go higher power too as a fill in translator?
Maybe. WGBH had to get consent from WTKK (then WCDJ) to accept third-adjacent interference just to get W242AA on the air in the first place. I would think Greater Media would take a relatively dim view of any attempt to significantly improve the facility's signal. Plus it's shoehorned in pretty tight against WSRS 96.1, too...that might actually prevent, on contour-separation grounds, any attempt to increase ERP on the xlator.
Would Greater media file against WRBB if they went to either 102.9 or 106.1. Granted Touch wouldnt be happy but pirates dont have any legal claims or rights.
Probably they would. Third-adjacent has lots of examples of peaceful co-existence. Second-adjacent? Not so much.
But the FCC would never authorize it in the first place. Remember that for grandfathered Class D's and ONLY for grandfathered Class D's, the contour separation rules dictate that the Class D's 80dBu F(50,10) contour cannot overlap the other station's 60dBu F(50,50) service contour. (for everyone else, second-adjacent interfering contours use the 100dBu, same as third-adjacent) WRBB is well inside both 102.5's and 105.7's 60dBu so I don't think the FCC would allow it.
I don't think it would really matter much, though. While 104.9 is not a good frequency, WRBB's real problem is the Pru. The campus sits just next to (or slightly within) the Pru's blanketing contours, and no Class-D station on ANY frequency is gonna have the ERP to "punch thru" all that blanketing.
IIRC, didn't WRBB also start having problems a few years ago when Northeastern put up a new building that was roughly the same height as the existing WRBB tower? And they didn't move WRBB onto the new building?