Mango Auto - First Grow Ever!

It's maturing, so it's sucking up nutrients (mobile elements, particularly phosphorus at that stage) from those leaves. Sometimes it's an indicator of the plant needing more of those particular nutrients, or that there's a bit of imbalance (like n itrogen excess) causing uptake issues. In your case, I think it's a ruderalis and I don't like them.

I've definitely stopped training her and just let her grow after the trauma. I don't water her unless she's dry, I do the finger test almost every day. When I took these pictures she was bone-dry, I gave her a watering with calmag. Since she's not doing too well and the trichomes kinda do need more time, should I give her one more feeding with both Bio Bloom and Bio Grow? (I know that she needs bloom nutes obviously but Bio Grow has more Phosphorus)

@TheUK420Show 's answer in your previous question, he is right, don't stress or do anything to auto's. Maybe exception for xxl autos. I see now both guys said it... What you have now is a magnesium deficiency, this is caused overwaterting (since you added extra calmag). if problem stays, the ground could be too wet or watering PH could be off. You are also at the end of your growcycle (maybe two more weeks for mango?), If you suspect the buds and trichomes need more than two weeks, I would help it out with some calmag and some extra phosporus. But check soil first, you also have drooping leaves and some signs of nitrogen defiency so I suspect they soil is waterlogged. If soil is wet (shouldnt be wet all the time, top should dry out). let it dry, careully give leaves some calmag solution. Dont wet the buds.

You want to flush when she is displaying aorund 10% amber trichomes. flush for 5 days then chop. It should be good then. Best Of Luck!