Agree, many vendors seem like to have no clue how to name it. I had a conversation with limitlesslifenootropics which is generally a very good source, and they insisted that their Thymalin is synthetic and their Thymulin (they sell both) is thymus-derived. But the formula they provided are the same, both seem to be tested to be a 9-peptide. Go figure. Others just sell Thymulin marked as Thymalin (for increased sales, I guess).
That "Thymalin" you quoted is a thymus-derived compound, having Vilon (as the main peptide) and also Thymogen, Crystagen, etc., all in 1%-5% proportions. No Thymulin there.
Anyway, be sure to take Zinc 20-50 mg (2 hours before if orally).
I would be careful about that mentioned PGB. They look suspicious to me.
Beyond Limitless, if you figure out what they sell, (their thymalin 100mg is 126.49 now), there is canlabintl, but it kind of expensive, and they don't publish COA so you have to trust. Also BioEdge has it 45$/10mg and they tested for endotoxins.