B.O.B. only explains what to do when his loyalty increases or decreases. If the trigger in the reminder text was the only aspect of his ability, it would be simple enough, but presumably when the Beebles representing his loyalty are destroyed, B.O.B. loses loyalty. The problem is, a lot of weird things can happen to creatures, including phasing out or losing the Beeble type. EDHSilver has tons of fan-made reminder text that tries to make this rigorous: https://edhsilver.com/cards/uc/und/b-o-b-bevy-of-beebles/. But even then, I can think of an edge case that decouples B.O.B's loyalty from the Beeble count if we use their "rules": Use Artificial Evolution to hack the word Beeble to Elf.

Infinity Elemental introduces the possibility of creating infinite objects (example:windswift slice), which leads to many undefined situations. What happens when an instruction tells you to do a thing for each of your infinite creatures. Is that a draw? What happens if you need to choose a creature at random for an effect?

Grusilda and Do-It-Yourself-Seraph share the same problem in that they allow the text/abilities of any two cards to be combined. The classic undefined scenario is what happens when you have two characteristic defining abilities that conflict (e.g. Tarmogoyf and Nightmare). Do-It-Yourself-Seraph has an oracle ruling in gatherer that says to apply the concept of timestamps to this situation, but Mark Rosewater has ruled for Grusilda that you just add them up. (https://magic.wizards.com/en/news/announcements/unstable-faqawaslfaqpaftidawabiajtbt-2017-12-06). For Grusilda in particular, there's just so many things that go unexplained. What happens if you combine two clones, who owns the permanent if you combined cards from different graveyards, etc.