In my brief dive into colorspaces I got the impression that CIELAB isn't actually that uniform and there are better spaces available, such as DIN99o (actually DIN 6176). Is this right?
There are any number of colorspaces that have been proposed that are better. Some are complex and ad hoc, such as two different releases of CIECAM. Others are relatively simple, such as Jzazbz. IPT also comes up a lot. I think the issue is that there isn't anything resembling consensus on which of these "more perceptually uniform" color spaces we should use. So a bunch of efforts, including freieFarbe, use Lab.