It looks like that editing a feature through SDK (for example a custom button) like moving a point in the correct position is not also moving the attached lines, there is now an enhancement request for this (ENH-000172547) but ESRI support suggested to also open this idea to gain traction.
In the old geometric network world, moving a point (or a line) would also result in the elastic movement of everything attached to it, we have a lot of tools in ArcMap that "fix" things around the network that now cannot be ported to Pro because of this limitation, and we think it should work like in ArcMap.
Note that the UN is properly configured, if you use the standard Move tool from ArcGIS Pro, things gets edited like they should through code.
So, please, work on that enhancement and let elastic editing work through SDK
Thank You
