TGCtools is opensource. My version has always rendered multipolygons just fine. I believe there is even work being done on a new "official" version to deal with that and all of the other OSM related issues. But that isn't what my comment was about.

Anything that uses a query to retrieve data from OSM takes a minimum of 20x more time when multipolygon relationships are used. This is the case with any app that uses OSM. It is a known OSM api problem. 

If I am on a course and using gps and OSM to track my shot, if it is a course with multipolygons, it is unusable.  Once you have an area with relationships of more than about 500 nodes, it turns into tens of minutes to retrieve even one hole (if the query doesn't timeout to busy servers).

If you want golf course geometries properly aligned and represented, please use the most recent elevation data available. Otherwise it is a waste of time.

Sometimes, even the courses have up to date imagery and lidar from drones. You can use JOSM and offline image sources to make them very accurate. I never upload my offline changes since they usually get changed back to whatever matches Bing and that work is specifically done for third parties that do not utilize OSM for anything other than the initial spline work.

