Is your SRS algorithm based on one of the published Supermemo algorithms? If so, is it one of the older ones like SM-2 or one of the complex ones that eliminates the "whoops I missed a day" problem?
Rather than make a custom deck for Anki or Mnemosyne, you're reinventing the wheel a lot by writing your own SRS. Is the main reason so you can have that awesome-sounding handwriting matching feature? Does that handwriting feature work flawlessly for native Japanese control groups? Have you found that the Supermemo/Anki/Mnemosyne approach of users self-reporting their accuracy isn't as reliable as using handwriting recognition?
As for marketing, there's a sizeable community of people already using spaced repetition software for learning Japanese, and they tend to be centered around forum.koohii.com and alljapaneseallthetime.com (although I'm not sure how much activity the latter gets nowadays). They use SRS to commit to memory the mnemonics in James Heisig's Remembering the Kanji. That community is probably the only place in the world where you can find multiple people who achieved competent Japanese literacy in a month or two. So show them what you've got and ask them how it stacks up to what they used and pick their brains for suggestions!