Hi WDNJSQ,
It is not recommended to downgrade the software version.
It is recommended to upgrade to the latest version to add new features, optimize existing features, or solve problems in the current version, you need to upgrade the device
For the V200R020C10 Features please check the version release notes: https://support.huawei.com/enterprise/en/doc/EDOC1100180385?idPath=24030814|21782164|21782201|24017529|250400208
The mentioned Software version V200R019C10 is not supported by the mentioned AirEngine5761-11, the stated version is supported with another AirEngine model.
I hope it helps!