Hi @James_Nyanga! As you are new to the community, when you get a chance, please introduce yourself here.
Glad you were able to figure out the constraints and thanks for offering to help others! The documentation here:
https://docs.odk-x.org/xlsx-converter-reference/?highlight=constraint
has a bit on how they work and also the reference applications that come with the tools have lots of examples for folks who want to know how to do constraints!