So I continue searching through Internet Archive, and found this interesting archive:
https://archive.org/details/koumakyou_old_patches
This one was posted by user touhou-memories (can't confirm whether they're the same person running this blog), which contains the following patches:
kouma_update009a_010
kouma_update010_010a
kouma_update011_012
kouma_update012_013
I'm not sure if they're legit or not, but they do seem to follow the same logic as the updater for version 1.02g and 1.02h.
They do not work with trial v0.08p, and based on the naming of these patches, we'll need v0.09a for the first two patches, and v0.11 for the third one (omitted update 0.12-0.13 because 0.13 is already available).