Can Europe train a frontier AI model?

It seems unlikely at the moment. The writeup you have is quite interesting, but notably distributed compute for frontier is at least a bump in the road.

As other's have pointed out, if resources across Europe came together there could be a good amount of resources today to do so, but it is fragmented.

Project Glasswing, and most recently the blocking of Fable 5 potentially only for non-US citizens have sparked more attention in the political spheres regarding sovereignty/competitiveness of European AI.

There as also this great write-up which explains the trajectory Europe currently has when it comes to AI compute here: https://europe2031.ai/

So theoretically: yes, but there doesn't seem to be a big enough will to attempt to catch up with the trajectory of American hyper-scalers.