The word slowly here is all wrong. It is true that ir + present participle has the sense of something happening little by little, but here it is a dynamic process, and the word slowly works against that. If you heard someone say: "Voy pensando que..." you would understand her to be saying: "I'm starting to think..." Not "I'm slowly thinking that..."
The translators in their preface don't comment on any stylistic feature of the work at all. The treat Claudio's poetry as inspirational uplift, and offer the usual biographical information.
I thought of this because I was reading a very dynamic account of the rhythmic dynamism of the music of Revueltas.