Is it possible to include fields at the Lemma or Senses level that may later support language learning?
I'm a daily user of wiktionary mainly because I've been learning languages already for many years. I would say that the use of wiktionary for my mother language could be a tenth or a hundredth compared to its use for second language learning.
In learning a language it could be helpful to be able query the wiktionary for sense by its frequency. There are frequency list already, but I've not seen yet one that does so by sense.
In addition to examples by sense, there could be a section, also by sense, supported by the learners community to include . For instance, mnemonic sentences and or images that may help while learning a word. This mnemonics could be rated by users, so that the most voted are displayed. Here there may be an option to set the mother language, since a mnemonic could be very good in your mother language is French but have not sense for someone that speaks Japanese.
With this data, some sister projects may be developed as learning tools, like learning cards, improved from what is already available outside wiki, using not only repetition learning, but good mnemonics.