Same uses as parent species. More than one species has yellow foliage forms, however the most common ones are from red elderberry - this is less suitable for eating than black elderberry. Look up preparation and use for parent species to find out what to do with fruits from your yellowleaf one.
Elderberries are diuretic. And are highly variable in this property. The European types are considered more "edible" than our native North American genera's. Tread lightly. The diuretic properties have been exploited for some years now, as a weight reducing strategy. This thread has got me thinking about "Sambuca".