I am sorry if this is considered spamming and I do not know how easy this would be to implement, but I think it would be great to be able to choose which language to set as a predetermined dictionary language dependent on the language that you are learning on the moment.
For instance, if I am reading a text in Spanish, German or English I would like the suggestions to be in Spanish, German and English respectively whereas if I am reading in Japanese or French I’d prefer the suggestions to be in English.
If nobody is interested, feel free to just ignore my suggestion.