We’ve been seeing errors across the board on FME Form - Workbench 2023.1.0.0 (20230825 - Build 23619 - WIN64) and FME Server for queries to Feature Services on ArcGIS Online. The error shown is more generic than what you shared: 

ArcGIS Online Feature Service Reader: Encountered an unexpected error. The error code from the server was '400' and the message was: 'Cannot perform query. Invalid query parameters.'. Details: 'Unable to perform query. Please check your parameters.'

Error has been inconsistent yet frequent. In some cases multiple attempts to query will overcome the error. 

I am also regularly seeing the same error as psl “The error code from the server was '400' and the message was: 'Cannot perform query. Invalid query parameters.'.”, and also find retries sometimes work. For my case it’s attempting to write to a huge hosted table layer (no geometry) so I believe the size of the layer has something to do with it (>4 million features).

I am also finding that “sum” statistics (not “count” statistics) in ArcGIS dashboard widgets are failing for this layer and I get a “Cannot access data” error. This only happens once I try to apply any updates to the original features created in the layer so I know that issue isn’t related to table size alone. I haven’t got to the bottom of it but it feels like something underlying is breaking in the hosted layer, and I only get the “Cannot perform query” error once I start seeing the error in dashboard widget statistics.

One thing that may help is adding a “Field Index” for the attributes you are querying in the layer - might be worth a try.

I’m not sure about the circular arc segments error but that does sound like you’d need to inspect the geometry more closely - try changing the features per request on your writer to 1 and see which feature it’s failing on.