the springs are intact for sure. The question of wrong springs also makes sense, How would I know if the springs are the correct ones? coil wire dia? or coil count or both?

The front seems a little saggy too when on the run,

FWIW, I replaced struts (with Bilstein HD) on a 124 wagon that bottomed a few times, and it stopped bottoming, didn't touch the springs. I'm about to do it again on another 124 wagon but this time I want to try regular struts, not HDs. Does anyone have experience with both struts? or with the non-HD struts on a wagon?

There is a spec on height to a certain point on the chassis on all models. If you have the height the springs have not sagged. I also seriously doubt anyone would put softer springs into this chassis.

Good shocks can even help weaker springs with age. They slow the rate of compression way down.