If you want an ID for this, can you get a macro app on your phone and take a much closer and more detailed photo of the flowers. At present, I have no idea.
Could be Haloragis heterophylla as you suggest. Maartje, have the flowers opened since you took the photos? This is a late draft. https://apps.lucidcentral.org/plants_se_nsw/text/entities/haloragis_heterophylla.htm
Haloragis h does seem very likely, I didn't realize male and female flowers would be so different. I have uploaded some photos of open flowers of another specimen, see this sighting : Haloragis heterophylla (Varied Raspwort) on 31 Dec 2018