I think I've resolved this. I was browsing through Soren Bjornstad's excellent "A tour through my Zettelkasten" and the associated conversation, and saw his response to a question about converting his html version to node. Which was to run:
tiddlywiki --load path/to/single/file.html --savewikifolder path/to/output/folder
I did this for the stroll.html file, and it worked apart from the startup message:
Warning: Plugins required for client-server operation ("tiddlywiki/filesystem" and "tiddlywiki/tiddlyweb") are missing from tiddlywiki.info file
I looked back to when I first got my empty TW to run on node. I found that I'd run this command:
tiddlywiki path/to/output/folder --init server
That created a
tiddlywiki.info file with the missing plugins. So I copied that file into my Stroll directory, and it now starts up without warnings. So far, Stroll seems to be working on node, including saving changes to the tiddlers directory in real time. Only time will tell if I've done this correctly, as I'm a relative newbie to TW!