The solution is may be here :
Change the units in the website, on the wind colour scale. Then the modification is automatically applied to the phone app and widget.
The 22nd General Conference on Weights and Measures declared in 2003 that "the symbol for the decimal marker shall be either the point on the line or the comma on the line".
Different countries use different symbols as decimal separators
You say: "This also makes the meter conversion inaccurate."
As I can see, there is no inaccuracy for KPLU runway length.
3650 ft = 1113 m , also 3,650 ft = 1,113 m or 3.650 ft = 1.113 m
I don't think that someone could ever imagine of a runway length of three and a half feet!
I have tried to change wind speed units in widget on iOS and it works for me.
I have changed kt for mph.
Change wind speed units on Windy website. First you must be login
Then select the unit you want on wind scale.
The new setting is saved in your Windy cloud. And it will be applied to your iOS.