First of all, sorry for my bad English.
I’ve done what you say, using QtranslateX. I don’t know if it works with WPML. Let’s supose you want to say “month” in English, and “mes” in Spanish. Go to Uji Countdown’s settings page, and write the next where it should:
[:en]month [:es]mes
That’s all. The timer will show “month” when the English version is shown, and “mes” when the Spanish version is shown.