Marcel also has yet to find the other edited subject (not too difficult, indeed...)
Edited? Amateur

All I need to do is
dig up how to find threads with pairs of users, cross-reference them for
topics started by me, find a good post (that's still a requirement) and let the fun start

Quick&dirty:
comm -12 <(comm -12 <(wget -qO- https://loyce.club/archive/members/45/459836.html | grep '<FONT COLOR=gray>' | cut -d'=' -f4 | cut -d'.' -f1 | sort -u) <(wget -qO- https://loyce.club/archive/members/185/1852120.html | grep '<FONT COLOR=gray>' | cut -d'=' -f4 | cut -d'.' -f1 | sort -u) | sed s/^/'https:\/\/bitcointalk.org\/index.php?topic='/) <(wget -q --load-cookies /path/cookies.txt "https://bitcointalk.org/gettopics.php?user=459836" -O- | grep -a '</li><li>' | sed 's/<li>/\n/g' | grep -a bitcointalk | cut -d'"' -f2 | cut -d'.' -f-3 | sort)
Result:
Pick
a post, move the topic to change the title, Merit the post, change the title back, hope it worked

Way easier than this.
Remember where it all started.
In fact, one of the mentioned conditions is not satisfied by that particular post.