I agree, the property in Romania is owned by the Duchy, and is available to let commercially for most of the year. No need to part with it.
Should the move to Windsor Castle happen, it will replace Adelaide Cottage as a Wales' home. Windsor is a large building, with no royal living their for any length of the time. The King & Queen seems to prefer to spend their weekends at Highgrove.
I think the Wales family could make good use of the private apartments at Windsor, and use it as their main family home. The property is large enough to leave enough space for C&C to use it as and when they need to.
The private apartments are also very private, and certainly not a goldfish bowl. There are vast private gardens. Access to the private apartments is available away from the quadrangle, which visitors to the state apartments get to see. In all their years regularly using Windsor, QE2 and family were rarely seen there, unless they wanted to be seen!