1. I see it in the database - it was written in German, which might not be appearing if you have English set as default language. 2. I'll keep thinking on a good way of integrating more options for the mnemonics. For now, I inverted behavior - whatever comes first gets priority. 3. This is fixed by #2. Go to your mnemonic, click edit, then resave it.
I like the solution you found for the kanjis where the database didn't find all the bits. I just experimented with 満, where 艹 wasn't available. But as you can see, somehow 両 is missing some bits. I can confirm that the mnemonics"work" for me. Sometimes I can remember the meaning of a kanji, or distinguish one kanji from a similar-looking, because the mnemonic comes to mind.
For example, I always have trouble reading/understanding 胡桃. But when I can recall that "Barbarian's (胡) peach (桃)" is the Japanese name for the walnut, it comes back to me. So sometimes I feel like having some mnemonics for kanji compounds like this would be helpful.
Not sure how this could be implemented to the site, but it should look similar to the kanji mnemonics, just with full kanji instead of the parts.