Also, when I use table editor in TURO, the grid is all wrong. The merged cells are still divided, and there are two cells that are blank and not recognized at all. This table will not pass regularity. In another table, the grid does not align, and some cells are merged together when they were not originally that way. I already changed the tags for colspan and rowspan in the tags, but these tables are still not passing regularity. If I use the table editor to select column and row spans according to what the grid displays, will that cause problems when the reader encounters it?
A regularity failure (irregular tale) can be due to a missing cell, incorrect span attributes, or incomplete tag attributes. I suggest checking with the PDF Accessibility Checker (PAC 2) and then review the exact error at the Section 508 Help Center at TaggedPDF.com.
A program such as axesPDF for Word can export a correctly structured and tagged PDF table, but the current version of Acrobat often does not. In fact, Acrobat's Tags panel can show a "TH" for a header cell and you think you are good to go, but a check with PAC2 shows errors. That's because tag attributes are missing or wrong.
To fix a PDF table, you may need to manually edit one or more TH or TD tags' Properties (Attributes). The Section 508 Help Center shows you how (short video as well as text) to fix irregular table issues. Those type edits has always fixed the issue for me, though they do get "down in the weeds" of PDF editing.
Below is an image of a sample attributes of "good" TH tag that spans cells.
Generally, the Table Editor can only display its grid accurately if the attributes of every TH and TD tag are accurate. Wrong or missing cell spans then cause a display problem. I normally avoid the Table Editor because of that and edit TH and TD tags as needed.
Another advantage of the free PDF Accessibility Checker is that the Screenreader Preview feature shows you visually how a screen reader will read out the PDF. That often shows you where an error exists. A sample of bad table TH tags that show up visually in PAC2:
The Screenreader Preview shows an empty TH cell at top left and (at least) a lack of span attribute for the top right TH. Now you know where to edit the PDF fix the irregular table problem.