SWIM has not messed around with the carbonate at all yet. I'm sure a similar cleanup step would work for mescaline carbonate. The same mechanisms should apply. Mescaline carbonate should be the most polar and least soluble molecule among the carbonates, so you need to find a solvent that is just polar enough to dissolve the impurities but not polar enough to dissolve mescaline carbonate. Try acetone, IPA, or MEK. It’s likely one of them will do the job.