The context window is only that sentence. It would be technically possible to increase the context window, but it would make it impossible to cache and increase translation costs even without that. Unfortunately the development of Nuenki has been defined by mitigating the cost of translation - before I had my many mitigations my prototype burned through six euros of credit in a day - so it's not practical to expand that context window.
I'll definitely recolour that button. Thanks for mentioning it!
The incorrect translations are the engine's fault. The version you're using uses https://www.deepl.com/en/whydeepl . Looking at my quality data for the new update (which adds Claude and Gemma as translation sources in some circumstances), that'll improve a little soon but ultimately not by much.
For a more practical complaint, in the Nuenki browser extension, the settings window has a primary-colored (green) button in the bottom right that says "Log out", but has no "Save" button. I almost clicked "Log out" when I just meant to confirm the settings I had made!
Edit: Also one question, if I may - how large is the context window for the translations? I noticed that the Chinese it generates sometimes feels a little unidiomatic, but I'm not sure whether that's due to too little context, the fault of the translation engine(s) used, or just my feeling as a non-advanced Chinese learner being off.
Edit 2: Some of the translations are definitely just wrong, too. Again, might be the fault of the engines - after all, machine translation, even in the age of LLM, is not perfect.