Yes, V200R006 is compatible with V200R008.
In the documentation, you can see this:
If a device is upgraded from V200R003 or V200R005 to V200R006 or a later version, the AP configuration will be lost. To prevent configuration loss, convert the configuration file of V200R003 or V200R005 to the configuration file of V200R006 using eDesk before the upgrade. Upload the configuration file of V200R006 and specify it as the startup file after the upgrade or re-configure the device after the upgrade.
For details, you can check the upgrade guide.
https://support.huawei.com/enter ... 775?idPath=24030814|21782164|21782201|250525922|250526784
After the configuration is converted using the eDesk, you are advised to contact the TAC for the R&D engineers to review the configuration again.