No, the whole idea of DIN rail is to allow speedy mounting of switchgear components.As to type testing clearly non type tested gear is not necessary dangerous and in real terms if one manufacturers gear fits into another manufacturers box then really no problem with using it as the whole idea of DIN rail was to allow one to mix and match.
A problem with "mix and match" is that if the assembly goes wrong, who gets the blame, the mcb manufacturer or the CU manufacturer? Sometimes devices don't work correctly (i.e., within their manufacturer's specification) if fitted in another manufacturer's CU enclosure, even if the busbar arrangement is compatible.
There's also the issue about physically fitting in the enclosure without leaving gaps that can allow contact with live parts.