Even though I flashed as you said with stochfonts.zip previously installed fonts are still there including these fonts.
Steps to revert to STOCK ROM,
1. Go to 'Settings'>'About'>'Software Info'>'Software number' and check the radio no.
Try LG Flash Tool 2014 and whichever version KDZ you want instead of you can still get into Download mode.
official LG G Pad 8.3 Lollipop 35A_08 5.0.2
official LG G Pad 8.3 Lollipop 35A_08 5.0.2 DEBLOAT SCRIPTS and copies of all the file...
It would be interesting to test if the issue persists with stock 5.0.2 on your tablet. If it is, it could be a hardware defect. Maybe the gyroscope is faulty.
For your information I was using this ROM(aosp_v500-ota-eng.adrianomartins_5.1.1_r1_201...
I'm not sure which statements you mean because you forgot to add the link in your OP.
But, standard manufacturer policy is (and I like many others find this totally unjustified) if you root the device your warranty is gone. You SHOULD be able to ...