Deep learning RNA sequences
The question of folding of RNA sequences looks slightly similar to protein folding - perhaps searching in this domain might bring more suggestions. 

An example of (current) state of the art of deep learning approach to protein folding is AlphaFold developed by DeepMind for CASP competition . They basically decompose the angles to an image representation and look for structures in the proximity of each atom. While it requires a significant processing power, RNA structures might be easier due to the size of the sequence.