You would need to add something to clarify your meaning. For example:
- Dych chi wrthi'n gwneud caws? - Are you [in the middle of] making cheese?
- Dych chi'n gwneud caws heddiw? - Are you making some cheese today?
- Dych chi'n gwneud caws [yn gyson/bob wythnos/yn aml]? - Do you make cheese [regularly/every week/often]?