So... Remilia can write English, but not speak it well?
Kosuzu is pointing out to Remi that it would be easier to just talk face to face now instead of writing since she came all the way to her store removing the need for the letter entirely.
Honestly, these illiterate commoners are such a handful!
.... Shouldn't we just have a normal conversation now?
I shall instruct her in English personally!
The response from Suzunaan to the letter in English is running late...