Why not contubernales?
Report it. It should be accepted, especially because it's one of the three choices in a multiple choice task.
Isn't the capitalisation of "Hispanice" an anglicism?
I would say it probably is. Latin orthography differs a lot based on the language of the intended audience. It also varies a lot depending on the period something was written.
Why nostri instead of nos?
nos is a pronoun, nostri is the possessive determiner/adjective in the masculine nominative plural form to agree with comites.
Is the -quu- not reduced in loquuntur?
Compare ubi and unde.
Why not 'contubernales'?
Which case is 'hispanice'?
It is an adverb.
Et ego scire debeo.
An "adverb"! Thanks a lot!
"Conturbenales nostri hispanice loquuntur" should be accepted
Try contubernales, maybe what you put was not marked right due to spelling.