Why is "I would often tidy. . ." not accepted, after the long lesson teaching that "used to" or "would" are often the most appropriate English translation for the imparfait?
It's just a minor omission, as every other possible location of "often" has been considered except that one. It's now added.
what's wrong with "I was tidying up my bedroom often?"
"I was often cleaning my room" isn't accepted, not sure if "I was cleaning my room often" would have been. I sort of get why (it becomes more of an 'etais' statement?) but clear breakdown would be appreciated!
This answer should be accepted because in AmE it is extremely common to have to "clean your room" when the implied meaning is "tidy your room". I'd say that's the most common way to say this -- I've actually never heard anyone I know in the U.S. use 'tidy' as a verb, and they rarely even use it as an adjective. I just checked with my mother and she agrees that she never uses the word 'tidy', only 'clean', or less often 'clean up', or even 'straighten up'.
I suppose it depends on what you mean by "clean". The verb "ranger" means "to tidy (up)", to put away. The idea of "to clean" is a bit different.
How about "clean up," which has essentially the same meaning as "tidy up" but is far more common?
"rangeais" is "imparfait". Why is then "would" to be used in the translation?
The imparfait is also used for habitual moments in the past. Think "When I was young, I would often do this" type of sentences. The "would" here is not conditional.