Function apply_renames 

pub fn apply_renames(log: &mut ObservationLog) -> usize

Rewrite RENAMES’d coordinate names in a log’s stored name lists.

Cheap, idempotent, and the difference between a renamed coordinate keeping its evidence and losing it: FitSet::build matches an observation’s stored names against the live feature set, so a name that moved takes every vote about it along unless someone rewrites it here.