Just some wild guesses:
Syntax error in devices.conf?
Restart tuya-mqtt after modifying devices.conf.
Are you sure that tuya-mqtt does support tuya-Zigbee devices (it isn’t obvious to me)?
Please note that tuya-mqtt is in ‘maintainance [sic] mode’.
Read on if getting rid of the Tuya-Zigbee gateway is an option:
Your devices might be supported by the Zigbee Binding or by Zigbee2MQTT (cf. Tuya ZTH01 control via MQTT | Zigbee2MQTT) - of course, one cannot be sure. You would have to buy a Zigbee coordinator to find out (my recommendation: Zigbee 3.0 USB Dongle Plus | ZBDongle-E | ITEAD STUDIO OFFICIAL - supported by the Zigbee Binding and by Zigbee2MQTT (experimental, but rock solid in my Zigbee2MQTT setup - YMMV)).