The leaves there continues to be stains and curl e...

Ok, your previous problem is getting worse... and it's now showing itself to be a potassium deficiency... and since you're only providing her with calmag, it's not going to get any better. You need some really good bloom nutes - these will provide your plant with what it is desperately missing - but it's not, as you suspect, a calcium or magnesium deficiency... she needs a small amount of nitrogen and a much larger amount of potassium and phosphorus which the bloom nutes will give you. Good luck!

And I see that you are using Biotabs. When you go into pre-flowering you need to add another Tab for every 5 liter soil. And repeat to give the Orgatrax (5ml per liter) and Bactrex (1 gram per liter) every other week. The last 2 weeks just tap water is okay. But during flowring the bacteria just do not create enough fertilizer to provide the plant with the necessary NPK nutrients.

This is not caused by overfeeding but it is very obvious that the cause for these symptoms are due a nutrients lockout from Potassium (K). Instead of writing a long story I can better send you a link from the Royal Queen Website with an article (with pictures so you can compare the symptoms) about everything you need to know about this. Here is the link: https://www.royalqueenseeds.com/blog-potassium-deficiency-in-cannabis-plants-a-how-to-guide-n671?_gl=1*mchec6*_ga*NDE2OTA4MDguMTY3MDk0ODA2Mw..*_ga_MFLBPT8N0L*MTY3MDk0ODA2My4xLjEuMTY3MDk0ODA4Ni4wLjAuMA..

Looks like overfeeding to me with hints of light stress. a hang height of 15" from plant should not be a problem for that light though. Might need to flush it out of the soil as best you can to correct the issue from progressing. Old leaves will stay damaged. I have had issues like this before on my plants and it did not help when I was over watering them. The leaves where drying out green and not burning "yellowing or browning" but getting real crispy and it was a problem with the ph of the medium and the amount I was watering. Good Luck!