I don't think it depends on Magellan, but on a different version of GCC, IcarosDesktop 2.2.8 surely has an old version of GCC, Icaros 2.3 included GCC v4.6.4
I was using IcarosDesktop 2.2.8 Hosted on Linux.
I believe the Build System for ABIv11 uses gcc 6.5.0 also. I don't believe the gcc version has much to do with the issue.
It may be an issue with x86 Native vs Hosted just like ABIv11 Native & Hosted for gcc. One works & one doesn't.
Maybe if you copy the Development directory from Icaros 2.2.8 directly into one of your AROS One x86 test system you can test the older gcc in a shell. If it does not work then something else is wrong. If it does work then newer gcc has issues with Native vs. Hosted & x86 vs x86-64.
By simple comparison the startup-sequence is different on Icaros than it is on ABIv11. The Package-Startup on Icaros does not include the assigns for Development directory. Those are located in Startup-sequence near the bottom. On ABIv11 the assign for Development is in Package-Startup.
One last thing then you can do your testing. The difference between a simple source code file & a complex one is not the lines of code or the size in kb. It is the number of includes. For example IconSplit uses no libraries other than studio.h, string.h & the other std library. It has 1500 lines of code but it compiles easily & it works. IconClone however has several system libraries such as IFFParse, Cybergfx, Datatypes, DOS, Exec, Icon & a few others. Maybe gcc has a problem finding the resources the application needs to run.