I don't see the County leasing part of its building to the City (now or in the future) as being a violation of the Skinner deed.  Nor would I see the leasing of any of the Skinner donation area to the (now) state court system as being a violation.

But I do see the county moving the Courthouse to the City hall block - outside the donated area - as a violation.

And I do see the County selling the butterfly lot to the City as a violation.

But if the City wants to lease the butterfly from the County, that might fly over the deed.

You should be prepared for the judge to take a very narrow reading of the deed and conclude that so long as the county commissioners retain their offices in the County's Public Service Building - within the donated area - they are in compliance with the deed.