@vidg Can you please check if Synfig 1.3.14 crashes the same way when you run it with Debug Console?
If you installed Synfig, then there should be a dedicated entry in your Windows Start menu to run Synfig with debug console. For portable version please see instructions here - https://github.com/synfig/synfig/issues/1442#issuecomment-633285479
Well what exactly do you want me to reproduce in windows using synfig?
I have seen that it is a link to a topic but I don’t know exactly what part.
@lobozamora 
I wanted to ask you to test file from this message and check if it crash for you (when you try to edit some spline in it).
By now I already got several people confirmed that it does crashes. ^___^