Office 365 update may fail because of missing proofing tools binaries for some of the languages.
We extended the scope of Office 365 bulletins to include proofing tools for additional languages starting from September 2021 Patch Tuesday.
Fixed in Patch Data starting from 7.3.849 version on September 10, 2021
If Office 365 updates are already deployed and failing after September 2021 Patch Tuesday, restart the Symantec Management Agent on targeted computers, or alternatively, if on 8.5 RU4, apply the point fix SMA_SMP_8_5_POST_RU4_v6 found in CUMULATIVE POST ITMS 8.5 RU4 POINT FIXES
For related issue, see Patching of Office 365 in languages not available in Patch Data import UI