Went back to Eder whatever. Located all seven spiral cloths. Touching the portal triggers a *different* sequence of partial shapes each time. Reasonable to number them 1 thru 7, smallest to complete. But which cloths correspond with which number, or pattern?
Glanced at hint guide online... which suggests right away having a 'friend' help. Better hint: when the Portal hasn't been triggered, touching a cloth displays its corresponding signal on the portal door. Trouble is, only a couple cloths have direct lines of sight to the portal. A couple others are near enough you can touch the cloth and run to glimpse the portal before it fades out... but at least two cloths aren't close enough at all. You can be reasonably sure of five at most.
Hint guide confirms basic hypothesis: you have to touch all seven cloths in the current sequence, before the portal activation runs out. But first you need to *see* the current sequence; after that, there's slightly over a minute before the portal deactivates. Can you run back and forth an touch all 7 cloths in a minute? Barely. Tried a couple times, didn't do it--but I may not be guessing correctly about the two unknown cloths.
Unfortunately, this puzzle confirms suspicion that the online game *does* require interaction between players, which for me conflicts with one of Myst/Uru's chief charms -- that you're in the role of an isolated explorer, alone, and can figure everything out yourself. It's as if you couldn't read a book without finding someone else to read the dialogue outloud.
Couple options... keep trying to do it alone, it might be barely possible. Or, go to the common Edo age and wait around for someone else to work the puzzle, and jump through the portal with them (as people were doing the other day).
Note also that, judging from hint guide, the adjacent Edo age has a virtually identical 7-cloth puzzle. But after that, the original Edo ages have perhaps different content (something about arriving at night).
Technical note -- got a couple crash errors, one a stack overflow.