If tool progression is installed alongside alfinivia, block breaking speed cannot be modified via alfinivia on a block by block basis even with no configuration changes being made to tool progression.

I have also crossposted this issue to the Alfinivia issue tracker.

I can't exactly remember, why the priority is LOWEST. I think, it had something to do with Game-/OreStages interaction. I've to check on this.

this won't work at all. if you reset the toolspeed without regarding the new speed (which is passed from other events btw) you need to run first of all (EventPriority.HIGHEST) or consider a different way of doing whatever you're doing.

oh i see now, it's because OreStages kills prior events setting the breakspeed. You can try loading after OreStages (add after:orestages to your dependencies) that should mean even if your priority is highest and orestages is highest, yours should run after.
EDIT: you already do this so it should be good now

For reference: DaedalusGame/Alfinivia#1

The fix will be part of TPr v.1.5.0, which is currently under review from curse.

That was fast. Thank you.