As someone who knows four languages[1] (picked every single one up during childhood) and is currently learning Sanskrit, I have to say that Krashen's input hypothesis and Orberg's Lingva Latina is probably the way to go if you are learning languages as an adult. The direct teaching method works but is time-consuming and generally used for languages that lead to an occupation, viz. English. The grammar translation met…
I built a tool[0] that gives you constant input at your level as you browse the web, so you don't need to take time out of your day. You can just learn a little as you browse, and let it compound over time. It works by estimating the difficulty of English sentences, then translating ones at your level into your target language. [0] https://nuenki.app
In Danish the third line is translated as "Du kan vende tilbage til oversættelser ved at holde musen over dem." which means "You can return to translations by hovering over them." i.e. the opposite of what happens. As a native Danish speaker I'd write "Du kan vende tilbage til originalerne ved at holde musen over dem.". I've had a hard time finding a translation that more accurately matches the wording of the original. The best I could come up with is "Du kan reversere oversættelserne ved at holde musen over dem.", but that just sounds like you're speaking English with Danish words to me, so I don't know if it's useful.
In French the second line is translated as "Plus la difficulté augmente, plus la traduction est importante" which means "As the difficulty increases, translation becomes more important.". Kagi Translate proposes "Plus la difficulté augmente, le volume de traduction augmente" and a few other things that don't look quite right to me.
I don't know how much this matters, since you'd probably end up exposed to a lot of different translations of many different sentences with this tool. Statistically, most of those will be correct and so you'll end up good enough understanding of the other language anyway.
In any case, you'd probably want to make extra sure that the examples on the front page are absolutely correct, so I hope you find my two corrections useful.
Oh! One more thing... when you select Japanese it says "Supports Furigana", but there's no furigana shown in the example. It would've been cool to see that on the example page as well.