Note you might be interested in looking at interactive machine translation systems and the associated research papers - for example Lilt [1, 2] or TransSmart [3, 4] - while those are designed for professional translators rather than for language learners, what they do is very similar to your long-term aims for this project (a specialized MT system that, given a partially written translation to the foreign language and some context written in in the user's native language, suggests the following word).<p>[1] <a href="https://lilt.com/technology/translate" rel="nofollow">https://lilt.com/technology/translate</a>
[2] <a href="https://lilt.com/research" rel="nofollow">https://lilt.com/research</a>
[3] <a href="https://transmart.qq.com/" rel="nofollow">https://transmart.qq.com/</a>
[4] <a href="https://arxiv.org/pdf/2105.13072.pdf" rel="nofollow">https://arxiv.org/pdf/2105.13072.pdf</a>