Larian can’t do anything themselves, it’s an issue with Steam Cloud. Other than causing a sync conflict to replace the already existing cloud saves there’s nothing you can do.
I'm fairly sure it's Larian's job to decide/set what data Steam Cloud is exactly supposed to backup, but either way, someone needs to fix this.
I have 1,5 GB of player profiles (with the respective saves etc) and 95% of this is obsolete data I have no use for.