You calculated the windspeed for variable called “Windspeed". The calculated value will only reside in that variable.
You cannot adjust values shown on tiles provided by apps, except for when you use an advanced virtual device as ‘mirror’:
At ‘Device’ you’d pick the ‘Vindmåler’ device, and at ‘Property’ select the wind speed capability:
You’ll need to install both Better Logic and Device Capabilities apps
Example of the result:
