Various bits:
1. Definitely read some Guy Gavriel Kay, if you haven't. Particularly Tigana (rebellion against sorcerous repression in a setting very like the city-states of medieval Italy) and the Sarantine Mosaic duology (rise of art and culture, a mosaic artist traveling to basically Byzantium)
2. Do we want to consider a "Technology" or "Science' skill? 5e has few skills, but one more might be workable. Not sure it would be appropriate for any of the classes directly (maybe?), but could be a background choice, especially for Sage and the merchant/crafter types?
3. Do we want to have a word to replace 'Saint' for the church? Simply to avoid real-world religious baggage- not necessary, but might be worth a look.
4. Languages: do we want to add any, for foreign nations, since races seem to be mixed in and national lines might be more important? At least one or two might be good- like Latin or Greek for medieval scholars, but not sure about current foreign languages. If we add any, do we want to correspondingly add some extra language slots, especially for certain backgrounds- I don't think it would be terribly unbalancing.
Relevant concepts would be a dwarven cleric, MC to Artificer wizard, as a sort of rune-magic user. A historian who uncovered certain texts on rune magic (which had been declared as heresy after the cataclysm), but also evidence that such magics had been used (long ago) for good purposes and to much acclaim- he seeks to understand the truth, and maybe someday to present evidence of his findings.
For ranger, someone who was the retainer of a noble family on their remote farm/estate- the family had no real soldiers per se, and their huntsmen took most such assignments, so she was trained to fight. When the family's youngest daughter was sent into the city for an arranged marriage which would help rebuild the family name (and resources), she was sent along as a servant/bodyguard. And when that daughter disappeared ("taken" by a wizard, either as a tool or an apprentice), she could not return home and has stayed in the city, taking mercenary work while she tries to find her missing charge. (Human Outlander Ranger, mostly- and could work just as well with straight PH ranger)

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.