There is a locale named az_IR which is the azerbaijani (az_AZ) which is one of LibreTranslate's languages only with other writing system. The words of az_IR are same with az_AZ, but az_IR is written via arabic letters while az_AZ is written in Latin letters. To translate az_IR, we can change its letters 1-to-1 to az_AZ and translate it from azerbaijani. I think we do not need to do something more to add it to LibreTranslate. Links to more details:
https://lh.2xlibre.net/locale/az_IR/
https://lh.2xlibre.net/locale/az_AZ/
az_IR wikipedia: https://azb.wikipedia.org/
az_AZ wikipedia: https://az.wikipedia.org/