Thank you for trying. Same here. So, after an UNINSTAL, CHECKINIs and a cold boot, a winning order appears to be:
I'm not sure that everything is installed correctly now (there's no ToolsByGoran entry in the "USER" INI). But after using INSTALL.CMD, without a warm reboot, the TEXTCONV.EXE, Initor nor FM/2's INI Viewer were able to open CHARSETS.INI. The reboot probably fully closes and/or unlocks the INI file. Please note that TEXTCONV.EXE doesn't use Rexx' SysIni() to test the INI file, which may somehow haved played a role.
Solved, without looking at a real cause.