So, taking advantage of the sales, i bought Trainz 2019 and both the Chiyoda Branch Line and Tokyo Metro 08 Series DLCs for a grand total of just 24€...
The transition between TZ12 and TZ19 is quite a steep one, so i'll have to get used to the new simulator, but i'm quite happy, as for the first time in my trainz history, i'm using the current-date version and not a years-old-obsolete one!
I'm also quite happy that my content works fine in TZ19, and looks relatively good, altough there's simply no comparison with others' stuff. Unfortunately, the old TZ12 content manager (and Trainz 12 altogheter) has given me the boot, so i'll have to slowly download all of my own stuff from my own website.
Both the Chiyoda Branch Line and the 08 Series are quite nice DLCs, but there are many things that can be fixed or improved (track alignment and smaller details on the Chiyoda Branch Line, textures and dependencies on the 08 Series), so i'll try making improvements by myself and i may relase them on my website later. Surely both DLCs aren't worth their full price, so my wholehearted suggestion is to buy them only when there is a sale going on.