it is pronounce locally as “lĕmʹ ĭnstĕr” not “lēʹō mĭnstĕr”
Or another way to think of it is Lemon stir.
Update ~ I’m using English (US) Sarah.
I don’t know, my grandparents and great grandparents, who are from the area, always pronounced it Lem stir - basically, the n is almost silent 
Hello,
Sometimes we can adjust pronunciations in specific regions… but only for certain of the voices on the app. Jane is the one with the greatest likelihood of success… UK voices, not so much.
What voice are you using?
I don’t really know; whatever the default is; certainly not UK. After last update, it seems as though there were two slightly different voices at different times
I’m using English (US) Sarah.
I’ve submitted a request for a revision of pronunciation for Leominster to the version we locals use.