I did repair my park last night...
I deleted all sunken supports and "broken" paths, smothed the terrain and rebuild the scenery. Stupid work I must say
Today I worked on a another coaster. Everything was really fine.
Then I have a single piece added on the existing main path. I did this with the path building tool and after that I built a new basic path at the new coaster station to connect it to the main path. Guess what happened?
The terrain surface was raised in the complete park (or the coster supports sunk again, I don't know!). All supports have created new craters and the whole park is ruined again...!
But this time I made a safety copy before.
The problem is: it seems to be impossible to connect the station to the path without destroying the terrain. This happens unpredictably and the error seems not to be reproducible.
There are no hills in the park near the path or the stations. Everything is build on flat terrain, all paths are completely flat from the beginning to the end...
Look at the following screenshots:
The first picture shows the park before the station (on the bottom right) is connected to the main path
This picture shows the sunken coaster supports (I enabled the water effect to clarify it...) after I connected the station to the extended main path.