[kqr]

I don't find it preposterous at all.

Yes, I would consider awk and sh lingua francae (?) alongside Perl – but in slightly different contexts, namely low-complexity jobs.

I find Perl slightly more suitable once things get a little complicated, mainly because it's footgun:power ratio is better than awk (few footguns, but also very low power) and sh (many footguns, not that powerful).

I have come across plenty of boxen where bc was not installed, so I don't put that in that bucket.

And yes, if I want to describe text changes in a highly portable way, I will use sed (or ed, depending on context) rather than, say, unified diffs. I could accept an argument that unified diffs are also a lingua franca for more complicated changes, but they are harder to write.