Hi Amy,
I know the product team was looking into updating custom forms recently, and so I checked with them and they said that in the short term, they won't be adding tables, but there is a major initiative to revamp the custom forms experience overall, and it's possible that things like tables may be included as part of that initiative. So this sounds like a great thing to add to the Innovation Lab to gather votes to make sure it's included in the overhaul project.
I hope that helps!
Kyna Baker
Workfront community manager