Shouldn't have much trouble geting your hose to fit on that Bosch adapter.
I had one years ago on a 5" sander but maybe they've changed ? [unsure] I recall it being a bit of a chore to slip the rubber Festool hose end over it but it's doable. These would have been the old style hose ends. Not the new and non-improved cleantec ends.
New hose ends are always tough to get over tool ends until they break in a bit regardless of the type and brand.
I still have that setup , but it'll be awhile before I can verify it because it's at my place a couple of states away. A also have one of the Bosch hoses from when they were $20 on Amazon there too.
What I remember is that both rubber ends ( FT and Bosch )are very similar is size. The Bosch is prob. a mm larger. But , it is more supple out of the box. It's still a tight fit on that RS adapter though.