I have looked though the thread about the CH pension system, and as a general rule it seems that it seems you can cash out your pension to pay for a primary residence.

That would initially limit it to CH and the areas just over the borders.

If you leave CH (for EU in this case), I guess you can withdraw pension to pay for primary residence there, right?

Does anyone know what the situation is if you are married and have split residence (getrennter Wohnsitz)? Can the pension in that case be used to pay for the foreign residence?

I think you'll find it is only for property in Switzerland as if you buy outside Switzerland you are no longer obliged to adhere to the Swiss rules but those of where your property is and these maybe different than Swiss ones. Swiss pension fund = Swiss property.

Not so.

A colleague of my wife withdrew pension to buy in France - she is still working in Switzerland.

She just wrote me that it was only pension paid in before you are 50 that you can withdraw.