Some of those objections to Contraction Hierarchies are possibly a little out of date. Modern variants of the technique allow for rapid live traffic customisation, see e.g. https://arxiv.org/pdf/2502.10519 . I suspect that the "nested dissection" approach also allows for regional maps.

It's been a while since I looked at OSRM's implementation, but I don't think they've been keeping up with the cutting edge here.