Can Recuva recover a file off of a sd card that has already been written to and had a somewhat large file structure?

Recuva
1

I recently attempted to mod my 3ds and accidentally deleted the 3ds folder, is it possible for a complex folder like it to be recovered?

2

If you have written to the card since deleting the data then it’s likely that the old, deleted, data has been overwritten by new data.

There is no harm in trying to see if anything can still be recovered - but I wouldn’t get your hopes up too much.

PS. Recuva Free would be all you need in this case, paying for a Revuva Pro licence would not give you anything extra to what the Free version can do.