Here’s my post with additional information and references to other 3d systems with similar limitations related to non-uniform scaling.
Initially I thought just as you did, but my research revealed a fundamental mathematical limitation that I think applies to your situation, too.
I don’t think it is generically solvable because Babylon, like other engines, insists on decomposing matrix transformations into Scale, Rotation, and Translation. The fundamental limitation, if I recall correctly, is that a sequence of SRT transforms, as happens in a parent-child relationship, cannot be expressed as a single SRT tranform when the parent S is non-uniform and the child R is not a factor of 90 degrees.
This is from memory, based on what I discovered when I did a deep dive researching the post I linked.