as you can see in the pic above, the BL is unlokced, otherwise i could not flash the recovery...
i also try
fastboot flash recovery twrp.img
fastboot boot twrp.img
but it's not working....finally i flashed the xiaomi.eu Multilang ROM for Xiaomi Mi5 (Unlocked BL only!) with miflash and after that the recovery starts into twrp!!! And with the last xiaomi.eu rom, also twrp was updated!