One thing I've observed is that whilst having words in Hiragana to read, it is in essence teaching your brain reading skills and not listening skills.
I observed this in a lesson I had with my tutor today where it is much easier for me to recall a word when I see it written versus when I hear it said.
Renshuu has a large number of sound samples of Japanese words, my feature request is instead of a word to read you have a play button for an audio sample of a word, then you have the normal four selections in English.
This way it is teaching you the ability to understand spoken words.
Sounds like a great idea to me, since it could be based on sound samples that are already there. I'm very slow at recognising spoken words and phrases even when I "know" them quite well. (Of course, I could just do more listening practice off YT or such... ) But I guess it would require a lot of extra work to put into practice?