Can you even reference sheet-specific names in another sheet at all?

Maybe you should duplicate all these sums in another cell of each
sheet, same cell on each sheet. Say, at the top of the column instead
of at the bottom. Then you can use a simple 3D reference, no named
range necessary. Make the Text Color white if you don't want to see
it.

Or, if the data is at least structured the same, make each Sheet long
enough to cover your needs and put the totals at the bottom of the
range in the same cell. You can hide rows to avoid printing/scrolling
extra rows.

Otherwise, if it is fewer than 30 sheets, I think you'll just have to
enter each cell or name as an argument in your SUM.