There are no ways in UFT... but there are two ways with a little 'detour'.
1. You can make a gedcom file and globaly change the tag CHRI to BAPT (or whatever tag there is for Baptisme)
2. If you have FoxPro you can change the event number in the DBF file from your project :-) this one is dangerous and only for the die-hard users of UFT. In the event library you can see which number is assigned to Christening and for Baptism then in the project file you change those event numbers.
Changing the role sentences is not such a good idea because when something went wrong the reference libraries are taken for the events and roles and everything will be messed up again (you will have Christening again).