Could you add Avar (ISO-639-2: av; ISO-639-3: ava) so that it can be selected from the drop-down menu, and a spellchecker can be installed.
Work ongoing on spellchecker here:
Many thanks :)
Eike Rathke committed a patch related to this issue.
It has been pushed to "master":
added Avar [av-RU], fdo#75161
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.