I don't have a good solution for you. But I know ArcGIS Pro treats the values in points and SDK expects DIPS. So if I take values you mentioned above convert points to DIPs, I get something like
```
dashEffect.DashTemplate.Add(10*1.33);
dashEffect.DashTemplate.Add(6*1.33);
strokeLayer.GeometricEffects.Add(dashEffect);
```
If you are reading from data sources that are not yet supported in ArcGIS Maps SDK you will have to add some extra logic in your app to adjust the symbology to match the original data symbology. Note, in some cases it might not be possible at all but for something like dashes you can try tweaking the dash template. Hope this helps.