Pozdrav @ Igor_Jurisic!
I’m also using a Xiaomi door / window sensor to keep track of whether my Toshiba split system is on / off. As you can see below, I have a Xiaomi camera positioned beneath the AC which was really helpful while I was testing things out. I still keep it there just as an additional method of checking 
Regarding some commands not getting through, I found the OFF command sometimes wouldn’t work, so in my script that turns off the AC, I actually fire the OFF command twice. I’m using a Broadlink RM Mini 3.
switch_off_toshiba_air_conditioner:
alias: Switch off toshiba air conditioner
sequence:
- service: climate.set_operation_mode
data:
entity_id: climate.toshiba_air_conditioner
operation_mode: 'off'
- delay:
seconds: 2
- service: climate.set_operation_mode
data:
entity_id: climate.toshiba_air_conditioner
operation_mode: 'off'
Cheers,
Petar