Summary

SLA date is showing in English
Steps to reproduce

Change user profile to Russsian
Browse any Service Desk issue that has SLA and notice the "-12w" instead of "-12н".

Expected Results.

JIRA should translate the week and month to

days - дни - д
weeks - недели - н
month - месяц - м

you see, for hours - часы - ч - all is fine.