Webform component map:
  node 27 cid 30 (COURSE)  -> course
  node 27 cid 27 (COMMENT) -> please_comment_on_any_aspect_of_the_course
  RESULT: both load-bearing components mapped.
-- cid 30 -> element_name course (the 20,397-completion path) --
  D7 cid=30 rows 20875 | D10 element_name=course rows 20873 | DIFF

-- distinct course values --
  D7 107 | D10 107 | ok

-- do those values resolve to migrated course nodes? --
  distinct values: 107 | resolve to a node: 101 | unresolvable: 5 | non-numeric: 1

-- element_name coverage --
  rows with an UNMAPPED element_name (must be 0): 0