Thrilling forum

Le scandale (1967) credited, as Christine Belling.

In nome del popolo italiano (1971) credited, as Lavinia Santenocito.

Frankenstein's Great Aunt Tillie (1984) credited, as Matilda "Tillie" Frankenstein.

Following a 12-year absence from the screen, Yvonne made a one-off "comeback" appearance. Unfortunately it is a rather lame horror-comedy not really worthy of her talents, though at least she did have the title role. This is her last known film appearance.

Found another French movie for Yvonne, called Le meurtrier (1963) credited as Clara Saccard in the cast list of the French website php88.free.f
It is based on a novel from Patricia Highsmith and it deals with two strangers who suspect each other of murdering their own wives and this results in a dramatic ending

Found this picture on the internet and you see her here in the car with her husband played by Maurice Ronet

here also a few posters

The last one is the original Belgian poster
The English translation of the title is "The murderer"

Versuchung im sommerwind (1972) a German movie, found only a Poster credit, as Claudia Bonhard, the Professor's wife (role to be confirmed).

Wuthering Heights (1958 TV movie) as Cathy.

Yvonne's name appeared in some publicity for this CBS TV production, but it seems that Yvonne was replaced at the last minute by Rosemary Harris. Apparently having already shot her scenes, Yvonne was fired from the production by producer David Suskind. A little more backstory can be found here. Every true diva should have been fired at least once! Thanks to Rudy for bringing this production to my attention

The Man Who Never Was (1966 TV series) - Episode 7: "A Little Ignorance", credited, as Paula Harris.

I've not been able to find this episode, but I did find the TV movie The Spy with the Perfect Cover, which is edited together from a few episodes of this series, including the one Yvonne appears in.