The problem with Gameranger will remain a mystery for me then. It’s a pity; it has lobbies after all.

There is no need to feel sorry about that. There are 98% of newbies playing there, 90% of whom are hardcore newbies going to the Capitol, and 8% are newbies who consider themselves "pros." And only the remaining 2% are good players. Moreover, there is a high probability that if you start playing with someone, they might just leave the game because they don't like that you take too long, or they might quit seeing that the situation is not in their favor.
I recommend arranging games here on the website in a specially created thread: /topic/10980/

It would be nice to have such a lobby/chat here for finding players in real time. Or built into the HD+ mod.

Having an in-game server for games within HD+, without any Hamachi, would indeed be great.