Thanks to all who added to the discussion.
An update on my personal situation, and what I've learnt from travelling to the South coast and meeting with an Everglides person yesterday:
My Edea had been ill-fitted. After having tried a mondo size 255 of medium width in my local ice rink shop, and feeling like the lenght was relatively fitted, we had decided on ordering the same pair with a B width (the narrowest Edea does). I brought the boots to Everglides, who confirmed that they are both too long and large.
We tried on quite a few boots and came to the conclusion that:
-A UK 3.5, (mondo 240) seems to work better for me than my actualy feet lenght of roughly 39 centimeters.
-The Risport RF4 seem to match my feet reasonnably well as they are particularly narrow (production stopped due to unpopularity as too narrow for most people, the model is still abundant on second-hand selling platforms).
-Riedell's Motion is a potential match, my size was not available but we tried on a pair about 3 sizes above just to get a feel of the width. Ideally I'd love to find a Uk model that I can try on without buying but that's gonna be difficult. I also think the model we tried had a C (medium) width, but I realized afterwards that Riedell's width goes until AAAA: my absolute (unreachable) ideal would be to try on all of their A + AA + AAA + AAAA beginners skates in different mondo sizes from 240 to 250
:')
- Because the surface of my feet is very... "hollow", rather than "padded", I ultimately will feel some "empty spaces" even in a skate that's as snug as possible.
Overall I learnt a lot of fascinating things as the Everglides staff really has an extensive, experience-based knowledge of skate-fitting.