Currently there is no way to process local file logs using the Windows Event Collector (WEC) as this is a limitation of the Windows Event Collector supplied by Microsoft Windows. The Windows Event Forward (WEF) can only collect logs within the Event Viewer containers at the moment.
An enhancement request has been opened with the One Identity team for possible inclusion of this feature moving forward.
The Syslog-ng Agent for Windows has the ability to collect local file logs. Please consider using the Syslog-ng Agent for Windows moving forward for local file and Event Viewer log collection.