Hi, sorry for writing in English but I am from Germany and can say some more things about Stellwerksim. It does not try to simulate an actual kind of panel signal box, but it just tries to simplify it and makes it possible to have different layouts from all over Germany and even Europe. Here and there are some signal boxes that are absolutely not correct in terms of correct track layout like in real life, but the level of quality seems to get better, and is very good in most places. But in most terms I can agree to greg86 and I would give it a try if you are into multiplayer.
If you are looking for a more realistic simulaton, go and try out Signalsoft, but some functions and operational actions are not like in real life, are bugged or simply not included, which is sad, because the price is very high, even from a Germany point of view. But anyway, if you want to go for more realism, you can go for Signalsoft, it actually aims to simulate real panels of the types SpDrS60 and SpDrS600.
https://shop3.signalsoft.nl/And in the beginning of this thread StellSi was mentioned: It has done a lot of progess in the last time especially in panel signal boxes, so that we can keep an eye on it in the future time.
I hope I was able to help you,
Oli