Good point on the lactic acid difference — store-bought low-fat buttermilk is more dilute to begin with and the fat has been skimmed, so you’re losing some of the lipid barrier benefit along with the bacterial content. I’ve tried both and honestly the skin response feels noticeably different. Traditional Takra seemed to calm my redness faster, but I imagine the store-bought version still does something if that’s all you have access to.

For dry skin I’d say yes, the astringency from Triphala can be a bit much. I found it pulled my cheeks tight in a way that wasn’t comfortable. Adding a bit more warm water to dilute the decoction before mixing helped, but I still wouldn’t use the Triphala variant daily in winter. For summer it’s actually nice.