s/vais/suis/
I think the point you are making is grammatical: in pretty much any language, the most common verbs are irregular.
But isn't this poem more about orthography and pronunciation? Some languages are much more regular than english in that regard.
> in pretty much any language, the most common verbs are irregular.
It's the other way around: if a language retains some irregular forms, then only because they're common enough that native speakers can remember them.
To be: I am. You are. [S]he is. They/we are.
Etre: Je vais. Tu es. Il/Elle est. Nous sommes. Vous etes. Ils sont.
Ser: Yo soy. Tu eres. El[la] es. Nosotros somos.
Estar: Yo somos. Tu estas. El[la] esta. Nosotros estamos. Ellos estan.
I think that pretty well sums it up.