Is this translation/interpretation a little too far away from the literal version? ‘You can’t imagine, how much your help means to us’ would make sense in English and seems closer to the Polish original? The existing translation makes it difficult to achieve the correct Cloze word.
It’s not too much of a literal translation, but I’d say it’s one of the preferred translations when “I can’t tell you” is used in this sense. You can see the Polish expression here as something close to “you can’t even imagine”.
If you translated it literally into “nie mogę ci powiedzieć”, Polish native speakers would understand it as something more like “I’m not allowed to tell you…”. But I understand your issue with this translation, it’s not very helpful in a cloze exercise.
By the way, another idiomatic translation of “I can’t tell you…” would be “nawet nie wiesz…” (lit. “you don’t even know”).
Thanks for the clarification, it is appreciated. Instead of reporting the sentence the next time I see it, I’ll just hope that I can remember the appropriate interpretation for the Clozeword.