Hi - the language output will be bound to the language set up for VirusScan in the Registry - so if some other language is configured, this is the language the log files will be generated in.
You could try using scan.exe extracted from a SuperDAT - this will always be in English. A downside to this, though, is that scan.exe in the SuperDAT is V5.40.0 which still uses the V1 DATs.
So it might be worthwhile getting the V6.0 product from the downloads site (you'll need a relevant grant number). That version uses V2 DATs just like scan32.exe does.
Hope this helps,