I have a question concerning the installation of the search help program ZGUIXTF4 and transaction ZXF4. Are there any risks if I grant all users the authorization to start transaction ZXF4?

When you start program ZGUIXT directly, or via transaction ZXF4, it displays a matchcode list that you can specifiy in the program parameters. No database changes are performed by ZGUIXTF4; it only displays the standard SAP matchcode. Since matchcode display is restricted by normal SAP security measures, for example in the HR component, there should be no security gap.