Is it OK to inquire about paper status after 7 months (2nd round) review?
I inquired the status about 4 months ago and only got a reply from the journal staff, basically saying that my message has been forwarded to the handling editor ...


is telling me that the journal has not forgotten about your manuscript. They are still processing it.

As you are well aware of, reputable math/applied math journals turn around time are very long in general. I have read on this site that two years is not unheard of. Please see this answer for example.

If you are anxious to know the status of your manuscript, I think sending another inquiry is okay since last time you inquired about its status is four months ago. I don't think the inquiry is too pesty. They'll understand.