The other side of that would be there was no mention of the installer saying to the client, we've had a look to move those pipes because of the bidet/toilet and they can't go in the wall because of A-B-C, so we need to cut the back out of your bidet .... so looks like it wasn't even considered.
It looks like the installer didn't check the units before it was too late and the tiling's done. I can't believe that any experienced installer would choose to cut a casting rather than move pipework. It could be argued that usually there wouldn't be bars like that in a typical casting, so the installer wouldn't have expected to find it and only saw it when it came out of the box when going to fit.