As Dave says, except that it is not a question of it being Italian or English yew (or Baltic or Spanish or American).
It is a matter of density and ring count.
Bear in mind that livery bows would have been made very quickly by (mostly) very skilled craftsmen.
It was neither economical, practical or even necessary to attempt to precisely follow one back ring on very fine and dense yew.
Steve makes too much of Italian yew, except that he is trying to replicate the probable source of the MR staves.
And like good Oregon yew they come from a location where one is more likely to find the right quality in reasonable quantity.
(And that he likes to promote it as a USP for his self bows).
With yew that is coarse enough in ring count that it is practical, one can follow a back ring, but with very fine ringed staves it is not necessary, indeed it can be highly impractical.
As long as the general line is followed and no radical departures made, it should not be a problem.
And very fine English yew does exist, it is just not at all common.
Rod.