I'm no expert by any means but if you mount a 50mm scope on high mounts then you may well start running into issues when you zero it (assuming you do that at 25yds/metres) as your elevation adjustment might be close to hitting the end-stop (generally not a "good thing"). Dependent on pellet weight - I guess you may have problems with lightweight pellets.
Also you're going to have a lot of holdover at ranges below your zero.
You can get around those issues by padding the rear scope mount prior to zeroing but I don't think you should need high mounts in the first place.
I'm sure someone will be along to say I'm wrong but I've never heard of anyone having problems fitting a 50mm scope to a TX200 - IMHO 50mm is perfect for hunting and that's probably what most TX200's are used for. I'd guess the FT/HFT springer guys mainly use the TX200/HW97 but they'll be in the minority of users.
I reckon whoever set the gun/scope up in the first place simply got it wrong