Currently, LO has as enumerated languages with full names the following language codes:
'Cree, Plains, Roman' -> crk-CA (this should cover both the circumflex and macron variants)
'Cree, Plains, Syllabics' -> crk-Cans
Ignoring the area code, the spell-checker modules for crk-CA and crk-Cans are not associated with the enumerated full language names. The spell-checkers can be accessed nevertheless with the language-area codes, i.e. crk-CA and crk-Cans.
For images, cf.
There was an ancient bug where this was due to an internal coding error on the Voikko or LO side, referring to something like crk-CN (i.e. with the wrong area code).
Don't know if this is the right place to report this, but reporting it anyhow for monitoring and hopefully eventual resolution.
This might eventually be handed over to The TechnoCreatives for detailed analysis and correction.