I have not found a good substitute for doing at least some of this manually, if you want to make sure it is done right (i.e. fully compliant with ISO 14289 PDF/UA). Automation is imperfect, but is worth a try to get you at least part way there. Options include auto-tagging from the source application (e.g. using the PDF creator plugin in MS Word), or the Autotag Document feature in Acrobat Pro. You could also evaluate the available advanced commercial (that is, expensive) tool sets that automate many PDF accessibility chores. The two that I am aware of are Axes PDF QuickFix and NetCentric CommonLook PDF GlobalAccess.
I was hoping for something like a macro to create a <list> structure with 10 <Li> and their <Lbl> and <Lbody>s
You can copy paste, not the tags, but the pdf content.
Only helps if you have more than 1 list. Make the first one and then from the PDF page, not tags, select all the list and then paste to other area. Then change the text of the 2nd list to what you want.
I find this a little easier than recreating several tags for each list item.