Hi Lazyhotdog,
Highway Blossoms 1.2.1 and 1.2 have been released now — the version numbers are now in full alignment, and the new 00-README.html file has the correct set of instructions for applying the patch.
Apologies for the confusion, and thank you for supporting Studio Élan.
(※ I would also like to apologise for the lack of official response until now — for some reason, it seems that itch.io doesn’t send notifications for comments here…!?)