It's a bit of a bodge mixing different manufacturers MCBs, RCDs or RCBOs into a different enclosure.
You're not likely to find many people on here who will advocate that.
Different manufacturers devices aren't generally designed to work together so the busbar may not line up correctly and you could end up not clamping down correctly on the busbar, for example. You may have to modify parts of the enclosure which isn't correct.
A CU is quite often only compliant with the regulations if it is populated with the correct switchgear designed for that enclosure. Otherwise, it is not compliant.
Sometimes you'll find a board or switchgear that is identical and manufactured by the same company but with a different name printed on it, and I confess I'm uncertain if the above statement about compliance with regs still stands if you decide to mix such equipment.
I wouldn't do it, personally, even if the RCBO physically fits.
