I will honestly be surprised if this gets fixed short of a pull request, and even slightly surprised if this gets a response (the fact I'm even playing on 1.7.10 when I know it's basically a fossil is only due to nostalgia), but nonetheless I at least wanted to document that there's a small issue with this mod's foci not showing up sometimes. I don't know whether it's on this side of the fence, yours, Thaumcraft's, or Thaumic Energistics', but when both the blink focus and TE's wrench focus are in my pouch, only one will show up on the selection wheel. If one of them is on a wand (or staff), the other will show up.

That is... a really bizarre glitch? o_O I can only imagine it's something in your pack causing issues, since I haven't had that problem in my testing world.

I'm not sure what could be causing it, but since you replied I tried to play around with a bit more to at least TRY to get something more actionable, e.g. an error message or stacktrace. Managed to get an NPE when I had both of them in my inventory and tried to equip one of them. Can you make any sense of this? From fnl-server-latest.log (which I was unable to upload in full because apparently it's too big):
Null Pointer Exception
unfortunately I couldn't seem to reproduce this exception on subsequent attempts, and I'm not sure how relevant it is, but it's a start.

just for reference, other Thaumcraft add-ons I have include: Thaumic Tinkerer, Thaumic Exploration, Thaumic Energistics (as mentioned), Witching Gadgets, Magic Bees, Automagy, Tainted Magic, and (technically speaking since they add research tabs?) Railcraft & AOB[T]D. Any of those stick out like a sore thumb as far as compatibility goes?

Maybe, but clearly it's between one of you, and information is so limited I wouldn't be surprised if they made the same assumption back. I did neglect to mirror this on their tracker like I had originally meant to, so I guess I'll do that now.
Yeah I realized that exception probably wasn't relevant after I started reading the stacktrace. Weird that it happened at the exact moment I tried to equip one of the focuses though...
That's totally understandable. Like I said from the start, I'm not really expecting to be able to fix this, but I did want to at least let you know it's happening. I assume you're having inaccessible dependencies from abandoned mods?

Thaumic Energistics seems like it could be the problem if they're the ones with the other focus? But I'm not really sure how. And that error looks like something to do with a Thaumcraft mob.

Also even if we figure out the problem, 1.7.10's dev environment is borked these days and I'm not entirely sure how to get stuff to compile anymore. >.>

It seems like the focus that shows is the second one found in terms of search order. Don't know if that helps but... ¯\_(ツ)_/¯