This is, apparently, intended behavior - some games have trouble with special characters in path names...
That is exactly the case. Many games have problems with special characters, or installation in Program Files due to the way permissions in that folder are handled. This is why the default installation folder is C:\GOG Games now.
But as I mentioned in a similar thread before - we don't block these anymore in new releases, because it turned out to be a bigger issue for users than we expected. Other games, already released in the new installer will eventually be updated as well.
Only the games that don't tolerate special characters will have them blocked.