The two bases may be to adjust to the proper pH, but I see that the formulas above differ in pH with no explanation. In any event, use of 2 bases is not that unusual. I don't rule out chelation from TEA, just not as its primary function doe to its weak power as a chelating agent compared to its strong power as a base.

Borate may offer some buffer capacity. Salicylic Acid is a weak chelating agent as well. It is claimed by some to offer protection to Ascorbates from oxidation by metal salts.