Hi @Ghisbar,
As far as i remember TWRP 3.4 was alway buggy, better is to use 3.3 or 3.5 or 3.6 or 3.7
For an upgrade from Q to R (without dataloss) you had to install first e-1.19.1-q, and then e-1.20-r.
But as you now have already formated /data partition, the way to recover your phone working should be flashing latest TWRP (or recovery-e) and then directly install e-1.20-r