Hidden Achievement Unlocked

So, I was browsing Steam this morning and came across this in the TSW2 page. What hidden achievement could it be?

 

We have 38 hidden achievements now. 30 of them are for the future Harlem Line, Horseshoe Curve and S-Bahn Zentralschweiz DLCs. Then there are 5 for the Class 313 DLC (looks like these are not available on all platforms) and somehow 3 for Sherman Hill. You can check the SteamDB page for more details.

 

It says, I unlocked it. I am not sure what I unlocked.

 

You can go to the list and check if one of the Class 313 or Sherman Hill achievements was unlocked.

Also, sometimes the ones for new routes can be unlocked for some reason. Once I got a RRO achievement for driving DB BR 422 before the preserved RRO was released. I guess the game just checked the 422 stats I got from HRR and gave me the achievement.

 

I found a bunch more of this Hidden achievements and they all correlate to the Tharandter Rampe achievements in the list. Its wierd because I achieved other rout achievements after and they display properly.