Hello!
I had some time to kill waiting for passengers and re-read my JAR-FCL (thanks to the miraculous iPad which allows me to carry around an entire library). Not a waste of time because EASA-FCL will be 99 percent identical to JAR-FCL.
There are exactly three mentions to (counter-)signatures in logbooks:
Time logged as SPIC and PICUS (1.1080) and differences training (1.235).
And the signature for the biennial training flight for revalidation of the SEP class rating gets written onto the back side of the license (App. 1 to FCL 1.1075), which as an instructor I can refuse to sign if I am not happy with the applicants performance.
All these JARs have been implemented to the letter here in Germany (and from experience I would guess also in France, Italy, Austria, Switzerland,...) therefore I think that the vast majority of European pilots happily fly around with unsigned and unstamped logbooks.