Keywords that stay consistent
One set of keywords for your whole archive. Tag something once and it turns up in every search, however you spelled it back then.

Build your list once
Nest places, people and subjects (Places › Philippines › Ilocos Sur › Vigan), add synonyms, and search the list as you tag. Bring your Lightroom keywords in and carry on from there. When optional AI suggests a term that's one of your synonyms, Mantle files it under your keyword instead of making a new one.
You decide what goes into your files
Keywords stay in your Mantle catalog until you choose to write them out. Pick whether the full path and synonyms go with them, so other apps see exactly what you want them to.