@VeryBadLlama Don't worry, a single trip on the RER B will put everything back in their original conditions.
@ParadeGrotesque
I was thankfully spared the RER C during my time in Paris.
@ParadeGrotesque
My experience of the C is that it's annoyingly infrequent and circuitous, but otherwise fine.
But I use the B daily, so maybe that sets a low bar in terms of predictability that the C easily clears...