If you call Lixil (Owner of Grohe, American Standard & some other names), they can confirm if the trim you choose will fit.
Should you decide the change the valve, they can help you pick one with the same rough-in so you might be able to work from the front with no tile damage needed. (They've got some where the rough-in box stays and the valve can be changed to one of many choices. Maybe yours is one of those.)
I don't know what country you are in, so instead of the USA number, attached is a list of all of Lixil's tech support numbers for the Grohe line.
Paul