Is Artio SEF open source? We only support sh404SEF at the moment because it is more advanced, open source and being actively developed.
Artio support may come at a later date, however right now we don't have time to investigate major feature additions so I cannot give a time frame as of yet.
EDIT: I just noticed that they provide a Free version without support. Update to the latest version -
ARTIO JoomSEF 3.5.3
- and see if it works then. Considering that sh404SEF has gone pay-only, we might work on this compatibility for the release of JoomlaComment 4.1 Alpha 2. But again, we don't have a timeframe for this release.