I don’t know if you ever received your answer or not, but my cream Legbar/welaummer I crossed, lay beautiful olive eggs.They will be sex linked because the hens are barred and the rooster isnt.
Cockerels chicks will be barred and pullets chicks wont be barred.
That kind of cross is a sex link cross not an auto sexing cross.
With the legbars they are autosexing because pullets always get one barring gene and cockerels always get two copies.
Welsummers are sexed by the eye stripes.
Crossing the two breeds will lose both of those things.
The chicks from your cross wont produce sexable chicks.
And if you reverse your cross using a legbar rooster over welsummer hens their chicks would not be sexable at hatch either.