In most instances, there's no point in recording how much time you spend per subject.
Course content may or may not be useful. Some colleges ask for course content as well as transcripts; otherwise, unless you're required to submit that to someone, no.
Below about 7th grade, I expect all children to be doing "satisfactory" work. :-)
I don't generally refer to children by grade level, as in "My 4th grader is in 4-H." However, when I have to identify my children by grade level (e.g, Sunday school, scouts, sports), I ALWAYS use the grade they'd be in if they were in school, based on their dates of birth and the cut-off date in our state. No exceptions. Grade level is an artificial way of grouping children of approximate age in a school setting; it has no real relevance in homeschooling. It can be helpful if you're choosing a school textbook for a specific subject, since "6th grade" means "children approximately 11 years old, give or take." :-) So, the year my children were 6 in May, they "entered" "first grade" that September. Of course, I had begun teaching them when I thought they were ready; I didn't wait for September. And I "promoted" in the fall, too: "Dear child, you are now 'in' fourth grade! Go forth and prosper!"
If nothing else, homeschooled children need to know what grade they're "in" so they can give an answer to inquisitors who only know how to discuss grade levels with people younger than themselves. :-)