Some more nitpicking remarks - but I hope these can be useful:
GUI looks impressive!
I'm also wondering why there are different sources for Windows and Linux - is using {$IFDEF Windows} etc not sufficient to keep one source version?
Looking at code like
PLT_WINDOWS = 1;
PLT_LINUX = 2;
PLT_MAC = 3;
ARCH_X86 = 1;
ARCH_X64 = 2;
// PLT_EXECUTABLE = PLT_WINDOWS;
PLT_EXECUTABLE = PLT_LINUX;
// PLT_EXECUTABLE = PLT_MAC;
ARCH = ARCH_X86;
// ARCH = ARCH_X64;
it looks like that could easily be replace with compiler defines (see
http://www.freepascal.org/docs-html/prog/progap7.html#x333-348000G so it's much easier to create one source version.
Looking at the source code zip, perhaps it's a good idea to move to sourceforge svn, git or hg and let people download the source code from there. Then you can get rid of all the sauvegarde, backup etc files that clutter up the system.
I would also recommend adding support for internationalization via .po files so peopl can start translating the strings - and e.g. English speaking people can more easily contribute.
Of course, I understand you're looking for volunteers to do work like this, but IMO this is not the kind of work you'd easily get volunteers for... so you are in a chicken/egg situation...