After a lot of fiddling around, I managed to build a working version. I had to fix a few bugs on the way, and I made minor changes, primarily to allow me to use %FBE_PATH% and %FBC_PATH% in the EnvironPath values already.
FYI: Very important bugfix: Opening an RC file would cause the whole thing to crash. The reason is your mod of ResEd's Project.asm. In line 255, you have to change "pop edx" to "mov edx, lpFileName". Another thing which would (potentially) crash is GenericOpt.bas, line 70 - "(@CmdLine)" must be changed to plain "CmdLine".
May I publish a compiled version for others to use? I guess it will be helpful.
EDIT: Hm, I just realize you wrote "known to me", so you are not the author - who is it then?
EDIT2: Found another bug: Setting a new font which has more characters than the default font will corrupt memory. In my case it corrupted the color list's constants and I was unable to use the option dialog. It happened because the default font names (e.g. "Tahoma", "Terminal" - they are supposed to be constants) were just overwritten with the new ones, but on the same memory address! I changed it so the structure holds the whole string instead of a pointer, which also required changing the INI load/save methods, but: I was unable to figure out how this works with other strings, though... because from first glance it looks like all string loading would crash sooner or later...
Actually I am (co)initiator of that SVN repository. The original intension was to continue FBedit development, but unfortunately I've never really started doing that. The majority of changes was done by a user with the username "ur", who is not active in any of the freebasic online communities as far as I know, but I should have an E-Mail address somewhere.
The repository is located on Sebastian's FBP server. He has also set up the repo and also is the only person who can change access permissions or add accounts. You could write a mail to him - I'm sure he creates an account for you so you can commit. However, currently Sebastian seems to have a lot of other work to do as I haven't seen him for weeks on IRC, so it might take a while.
Another idea is creating a github repository and continuing there. The last commit to the svn repo was in september 2014 by "ur". We should notify him and the other committers in this case as far as possible.
The repo started with an already modified fbedit version by "ur". I guess he hadn't used a VCS before that, because he commented out old code and marked changes in the source. There are definitely some useful changes, but - as far as I remember - there were also some changes that seemed very specific for his use cases. Ideally the changes since the last "official" version should be reviewed.
I'm sure there's no problem with publishing new binaries as KetilO is inactive since years and the project is currently basically dead. I just wouldn't call them "official" builds.
If the build system is working I could add a job on my jenkins server, where the fbc nightly builds are built.