That error uses to point to INFA_HOME pointing to a wrong directory.
You're mentioning you've set INFA_HOME to the path that is shipped with infa package, but it must point to the path chosen when installing. That's the path where directories "server", "tomcat", "services","java","isp",etc... are.
Have mentioned JAVA_HOME, not INFA_HOME.
Oh, sorry. You're right.
It's ok with JAVA_HOME then, just try by setting INFA_HOME rightly.
Since you have mentioned that this issue happens only for users other than the user who starts Informatica, It is possible that the error happens due to lack of permissions on the infacmd configuration folders.
Could you please provide 755 permission for the user with which you run the command on <INFA_HOME>/isp/bin folder and its sub folders and retry?