it depends if they want case-sensitive or not. My example was case-insensitive and would find the word WE unless using $findtokcs instead of $findtok.
However your regex finds the 'we' string within words
//echo -a $regex(oh what a swell weekend we had!, (^.*?we)) | echo -a $regml(1)
result: oh what a swe
//echo -a $regex(oh what a horrible weekend we had!, (^.*?we)) | echo -a $regml(1)
result: oh what a horrible we
this regex finds 'we' has a complete word:
//echo -a $regex(oh what a swell weekend we had!, (^.*?\bwe\b)) | echo -a $regml(1)
result: oh what a swell weekend we