There is a new release of checkit_tiff (v1.4.1) at https://git.fsfe.org/art1pirat/checkit_tiff/releases
. The error output for ASCII type tags now also includes a hex dump. For more information about the changes see the URL above.
Attached is a screenshot of how checkit_tiff looks with the "-c" (color) option.
In the meantime the bugs I reported to the ICCProflib have been fixed.
With kind regards
PS.: Under Windows there seem to be problems with the JS variant, if checkit_tiff itself and the config and TIFF files are not on the same drive. This is not a bug of checkit_tiff, but a limitation of NodeJS.