>At some point you want to go back to using your mother tongue.
It is an interesting point. When you first learn words in your mother tongue, you don't do it by outside reference to another language. Why is it different for you when learning a second language?
In your native language you don't (generally) have a specific goal to learn that word. Unless you feel compelled enough to look at a dictionary or ask someone for a definition (which is basically equivalent to looking at a translation in the language-learning context), you often just live with an incomplete mental model, until it becomes gradually refined from repeatedly hearing/seeing the word in context.
This is required, to some degree, to become fluent (i.e. intuitive) in a new language too, which is why there is an emphasis on immersion/input in most language-learning circles/ideologies. But when you have an explicit goal, you're more likely to be compelled to want the mental shortcut/jumpstart that a translation provides. There's also the fact that, as a language learner, the context itself often isn't understood very well (or at all), which makes the natural process even slower. This is where the idea of "comprehensible input" comes into it, see: https://en.wikipedia.org/wiki/Input_hypothesis
It is an interesting point. When you first learn words in your mother tongue, you don't do it by outside reference to another language. Why is it different for you when learning a second language?