Thanks a lot!
I've tried, TWRP seems to be sized correctly, framebuffers are unchanged. Touches in the unused area don't work, but now fit the displayed buttons.
framebuffers in 300dpi recovery:
Code:
# cat /sys/devices/platform/rk-fb/graphics/fb*/screen_info
xres:1024
yres:758
fps:0
xres:1024
yres:758
fps:0