Hello, friend!
According to the information you provided, the U2000 version is V200R015C60SPC200 and the OLT version is V200R19C12.
After confirmation: The U2000 version is incompatible with the MA5800-X2.
You are advised to upgrade the U2000 to V100R017C60SPC2017 to support the current OLT version.
The U2000 software version has been removed from the shelf. If you need to upgrade the U2000 version, contact the local representative office.
Thanks!