My bathroom is being professionally renovated and we chose to put in glass block windows because of the window in the shower area. They put them in and now are having to build in the sides of the windows/sills and in return covering the edges of the glass blocks, making the windows much smaller. Is this normal? Or can I have them redo part of the sill?
That's just how it goes.
They'd have to re-frame it at this point, with that specifically in mind (and still there'd have to be a piece of trim covering some of the window, to hold it in place). The window sill/opening could be bigger, but the view 'size' won't change.
In a masonry wall, the framing didn't allow for it (carpenter's fault).
In a stud wall, that's just how you do it. You can't fasten glass bock windows like regular ones, unless they have tabs.