If I have <<borrowers.primary_contact_method>> in my HOLD_SLIP, the primary contact method in my patron's record will be shown by its code instead of the description, wich is a problem for a non-english Koha. Right now, for exemple, the slip will say "Phone" instead of "Téléphone principal" even tho the rest of the slip is in french. Thanks
You will need to code the translation from code to description in your notice. There are examples for other values on how to to this using SWITCH/CASE on the wiki: https://wiki.koha-community.org/wiki/Notices_and_Slips_Library