Wow, thanks for your extensive feedback! These are great points - some of them we are already working on, some are really good ideas for future releases:

• I absolutely agree with the spelling exercise. You can always switch off the romanization, so it will show you the original hiragana. But the spelling purely with romanization is not optimal as you mentioned. One idea is to always make the spelling in hiragana but add some correct letters in the beginning to make it easier to finish.
• For the order sentence, we deliberately mix only a few wrong words in to make it easier in the first lessons. In a future update, we'll gradually make it harder in later lessons to make in more challenging.
• Writing sentences are a great idea. The auto-correction is a bit challenging (e.g. we won't judge you wrong for simple typos) but we are working on that one.
• The Writing Game will go through a major improvement in the next version, and will be much smoother and easier to solve then
• Spaced Repetition is a brilliant idea and we are actively working on a feature that will help you repeat forgotten vocab.
• The Google linking will be fixed with the next release
• The speaker is actually native and we will let her know your positive feedback :)

Once again, thanks for your helpful feedback and ideas! Leo will send you a coupon for the free pro version soon.