Search the label GET_SUFFIX in the REXX procedure TAUCMCLI and adapt the named library types and/or languages in the exit to link them to the correct file suffixes. The Editor used to open a package component depends on the file suffix. For example, in TAUCMCLI the ChangeMan library type SRC is linked to the file suffix COB by default. Without customization, all package components located in type SRC would be opened with the COBOL Editor.
In addition, adapt the list of dependent library types to your needs. Defaults are LOD and LST.