What does the top of the CP look like ?? -- there are several fixes and which fits you best is really a matter of opinion.
1) you could drill a hole through the Panel and use bolts and screws that go through the top of the panel and tighten from the under side.
2.) fill the holes with wood putty or sawdust and wood glue let dry and cure - sand level with the rest of the panel and reuse the current screws - Once the wood filler dries it will pretty much be as strong as the original wood was so should work fine but may eventually do the same (at which point you can refill again)
3.) Fill holes as above but for mounting use the other screw positions ( ie. your pic of the joystick shows 2 sets of holes the ones you used that can reposition slightly and the non used ones which are round holes in the mounting so require a bit more accuracy on placement - but using them would mean a new mounting position in the panel so would be like mounting in new wood since you are using a different hole location.
4.) Use a combination of #2 and #3 - fill holes and use either both or a combination of both hole locations in the mounting bracket - by reusing the original holes to mount and then adding additional screw in the non repositional holes in the bracket to hold it in place you add extra support for the joystick mount.
5.) get a small metal bracket to cover the area - and mount joystick to the metal bracket and use holes in CP to cover screw heads in metal bracket and then use new screws through metal bracket and into second hole position (those mentioned in method #3) to mount joystick and metal bracket to CP.
6.) get some threaded inserts and position them so they fit in the CP and give you threads to screw the mounting screws into - similar to pic shown below :

Figure any one or combination of the above should work and there are advantages\disadvantages to each but there are many options available.