Originally Posted by teorema67
I'd like to ask again: Is there a way to sync Omniweb bookmarks with iCloud (Safari, Safari for iOS)?
Not exactly. However, you can add your Safari bookmarks to OmniWeb by choosing "Import Bookmarks…" from the Bookmarks menu. It will add a new "Safari Bookmarks" group to your OmniWeb bookmarks sidebar which will refresh every time OmniWeb is launched. (It might refresh at other times too, but I haven't used that feature since we wrote it years ago and forget how it works.)
By the way, OmniWeb's bookmarks are stored as an HTML file, with some extended attributes on the anchor tags to support the extra features bookmarks use like specifying the interval for automatically checking a bookmark to see if the page has changed. This means that you can open the OmniWeb bookmarks file in any web browser and get a readable and usable (though not beautiful) page of links.
Hope this helps!