Thanks @Richard_Sather 
Well, concerning the subtask data in Report, I’m not so sure how it would work, actually.
I know subtasks are technically included in Charts (Including Subtasks in Dashboards - #30 by Zemeng_Li).
But if you want to make advanced charts, you might need to use custom field(s) - for example, the “sub-sections” doesn’t seem to allow reporting.
And unfortunately, the Proofread feature won’t let you fill the custom field while adding the comment (you need to add it separately, either in the subtask details, either in the project while subtasks unfolded).
Maybe there are other ways 