I know damn-all about music of any description, but am by way of being a rather annoying grammar pedant; and in my estimation: irrespective of "translation" matters -- no way is "sheep may safely graze", a split infinitive. Writing of allowing said beasties "to safely graze", would be such; but one can frame the thing as "may safely graze", or "may graze safely" -- or "safely may graze", or any other tormented word-order, should one be attempting rhyming and rhythmic verse -- and it's fully acceptable grammatically.
The general view nowadays: is that in the first place, the whole "split infinitive" thing is baloney; it did not exist as a taboo before -- not many centuries ago -- various learned and influential scholastic idiots got the idea into their heads, that English grammar should be brought as closely as possible, into line with Latin grammar. With the two languages being very different from each other, and operating in very different ways: I think it's Bill Bryson, who remarks that this edict from the eggheads concerned, makes about as much sense as trying to play football by the rules of baseball. The infinitive of verbs in English, involves two words -- "to love". The Latin equivalent -- basic form of the verb -- is just one word: Latin for "to love" = amare. The command came from on high, that because a Latin infinitive thus cannot be split; an English one may not be split. Lunacy !