We can discuss this further but here is feedback from my engineer:
for QTP: is likely to have some recognition problems with app built in C++ Builder. This is because C++Builder is not using standard MFC controls but customized versions of those. That means that QTP will probably work, however it will also have some limitations;
for WR: I've seen 2-3 accounts over the years who have seen good support for Borland's C++ using WR with the Delphi Add-in. Apparently their C++ classes are extremely similar to their Delphi classes so that WR should work fine.
Having said that, C++Builder is not an officially supported environment so if any problems come up your customer would be on their own outside of leveraging the resources in the knowledge base.