Correct, you cannot make relational queries.
You can try a two-step query instead (query the components, change selection to the comments, query "IsSelected AND ...").
Or you can use a spreadsheet-augmented method. Query Components, go to List, select and copy the columns including designator, position, rotation, etc. Paste into a spreadsheet. Query Comments, do the same. Cross-reference the two lists (they should sort to the same length and positions, but use e.g. Excel's INDEX(MATCH(...)) combo if not), and finally prepare a query string of exactly the Comments you need to adjust.
Note that, in the Inspector, you can enter "Rotation+90" in the Rotation field to rotate counter-clockwise, rather than setting all of the selection to a constant. Or you can make the change in the spreadsheet, and copy it back into the List Panel.
I don't think I do this much myself, but I have used similar approaches to set component placement, say when multi-channel doesn't quite work in the design, or when copying placement between files. Or when placing, say, labels and graphics over test points, to make a drawing of them. And similarly in schematics, or with the spreadsheet view (T, R).
So far, this has covered enough cases for me, and I haven't had any jobs so massive or strapped for time, that I had to do a more involved (scripting based) method. But if you're interested in scripting in Altium, that's absolutely an option!
Tim