The phenomenon our MC observed in the werewolf language where intonation is replaced by clearer vocabulary and syntax when transitioning from old werewolf to modern werewolf is an interesting mirror to the real life tranformation of synthetic languages from a synthetic syntax, that is languages that form sentences by stringing root words together with prefixes and suffixes, to a more analytic syntax, with clearer grammar that doesn't rely much on complex morphology to convey meaning. English is a good example of this.
There are some theories why this happen, a common hypothesis is that as borders open up and people start learning other languages, they find clearly defined syntax much easier to learn. Another hypothesis is the natural evolution of languages being a cycle of transitioning between being synthetic and analytic, with the evidence being some languages such as modern Chinese are actually more synthetic than their older, more analytic counterparts.