not really ...
Adds a fitpoint spline entity by using the simple API.
You don't have to store the result in a variable called 'SplineObj...'
Here an undeclared one, remark that we use variable names starting with a lowercase.
Unless you need that as a reference of the created drawing entity for another purpose.
The reference would only be valid without using a transaction to group additions/modifications to one action.
If you want to do further modifications, you can do that on a lower mathematically level before entities are added.
The 4 splines are not really 'connected' so the corners are indeed open.
The left one ends at (102,1000).
The top one starts at (120,1050).
That ends at (800,1040).
The one on the right starts at (900,900).
And so on.
I know that splines with control points can be tweaked to have hard corners.
With 3 successive control points at the same spot.
But that won't serve your needs as it aren't fitpoints aka 'raakpunten'.
It is not good practice either.
QCAD can not trim your splines pairwise.
There is no natural defined way in how a spline should continue beyond its endpoint.
The attached dxf includes polylines. It seems L-T-R are trimmed pairwise.
The ending segments of polylines from exploding splines are approximations of the local curvature.
Those ending arcs depends primarily on your explosion (XP) preferences.
Both ending arc segments can indeed be trimmed pairwise.
Still, that isn't a natural continuation of the original splines themselves.
QCAD can trim fitpoint splines that actually cross another entity.
Remind that when trimming fitpoints splines, control point splines are returned.
That is to keep the tangent of the spline in the intersection point.
Thinking outside the box:
Your splines are each defined by 3 points.
Maybe a 3-point arc would serve your needs.
The differences are very minute.