Essentially the problem is stated in title. The "Wand Prototype" feature should let you infuse an artificer cantrip into a wand at level 6 and two cantrips at level 14, then you get to add your intelligence mod to any damage. Technically it is the wand that lets you cast the cantrips, so they should add a wand to add to your inventory and name it "prototype wand of fire bolt" or something. This becomes complicated at level 14, however, as you'd then have to either:

1) Make a wand with every possible combination such as "Wand of fire bolt and shocking touch" and "wand of fire bolt and spare the dying" and "wand of fire bolt and mending" etc. This would require making a lot of magic items and I doubt DnD Beyond wants all the clutter

2) Make a wand of each type, and character can just add 2 different wands to their inventory at level 14. Not ideal or an actual reflection of how the feature works, but it would work.

The easier and less clutter filled way to do it would be to add a "wand prototype" to your inventory at level 14, and just let the character choose the cantrip option (or two) right there in the class feature and add the intelligence mod to damage on the cantrips selected

They are working on this. They are deciding the best way to implement it (either as an item or a drop down), and want the extra cantrip to reflect the bonus damage. They didn't want to delay the class further, so released it without the feature.

Has there been any update on this topic? About to start playing an artificer and would like to keep track of my spells.