Maybe the larger site/forum regarding TS. You can find there a lot of usefule hints and info’s.
Passionate community of italian simtrain fan.
Probably the wider italian community of train sim, with a huge forum and library.
Small italian community related to TS2017 and TSW, really active in route, assets and scenarios creation, especially for italian railway.
Nice spanish website, with good presentation and info.
Wide german site on train simulation, very useful information there, even if only in german language.
German webiste specialized in MSTS