@shang he,
Wow, this has amazingly quantifiable factors. Not used to this with language.
my approach would be to comply with the rule and look for three, four and five letter words stating with t and containing a schwa equivalent (e) and use a crossword puzzle word generator (use Google and search) and throw out all polysyllabic (as there is only one vowelthere are few) and long e sounding words. (this could be done by ceating a spreadsheet)
I'd write down the number of examples (with a good dictionary I'd bet there may be beau coups).
Get a phonetic translator sheet and translate.
As for vowels being tense or lax--I need a definition.
And the summary is on you, bub!
Rap