You can update the platform.xml in a save way manually from TWRP like described in 4b) of this guide: ✏ Update Guide for a modified FP Open OS (with Gapps, Xposed and more)
You can update the platform.xml in a save way manually from TWRP like described in 4b) of this guide: ✏ Update Guide for a modified FP Open OS (with Gapps, Xposed and more)