It’s not a typo.
Your question relates to breathings, not accents, of course.
In the first line, the basically “dactylic” meter requires that ευ- in εὐρύχορον be treated as a diphthong, giving the word the metrical shape _ υ υ _.
In the second line, ευ- in ἐυτρόχοις must be two syllables–not a diphthong. That’s why the breathing is placed over the ε, not the υ. Some editions would use a diaeresis to make this clear, printing ἐϋτρόχοις, but this would be redundant. -δαι σατίναι[ς] ὐπ’ ἐυτρόχοις has the metrical shape _ υ υ _ υ υ _ | υ χ.
It’s not unusual in Homeric hexameters for ευ- to be treated as either one or two syllables depending on metrical considerations, and this poem (the marriage of Hector and Andromache) is almost certainly echoing epic language and meter.
Both of these lines are the same meter. The first two syllables are the “Aeolic basis” and can be either long or short (x x). Then we have _ υ υ _ υ υ _ υ υ _. Finally, υ x. So the whole verse looks like this:
x x | _ υ υ _ υ υ _ υ υ _ | υ x
The most common Aeolic pattern is the glyconic: x x | _ υ υ _ | υ x. Sappho’s meter in this poem can be viewed as an expansion of the central element of the glyconic _ υ υ _ (a “choriamb”) by inserting “dactyl”-shaped elements. (However, it’s wrong to think of this element as dactylic–that’s why I put it in quotes. It’s actually a succession of longs and shorts, with no division into dactylic “feet”. It could just as well, or as wrongly, be described as expansion by appending anapests.) Instead of expanding by inserting “dactyls” (or appending “anapests”), the basic glyconic shape can be expanded adding “choriambs”: elements shaped like the central element of the glyconic: _ υ υ _, to get verses shaped like this:
x x | _ υ υ _ (_ υ υ ) ( υ υ _) | υ x
(Horace uses a Latinized version of this meter–the “Greater Asclepiadean”–in the famous poem that begins: Tu ne quaesieris, Leuconoe, quem mihi quem tibi and contains the phrase carpe diem.)
In contrast to the hexameter, Aeolic meters are isosyllabic (i.e., each verse in a particular metrical pattern has the same number of syllables, with no substitution of two shorts for a long). However, there are obvious similarities of Aeolic meters like this one to the Homeric hexameter, and some think that the hexameter emerged from “Aeolic” meters like this, though of course there can be no certainty on that point.
Here, I suspect, it’s the other way around–Sappho has consciously chosen to use an Aeolic meter that has a similarity to the hexameter. It’s difficult not to think that the pathos of this poem has some relationship to the tender and moving scene between Hector and Andromache in the Iliad: was Sappho inspired by that scene . . . or was the passage in the Iliad inspired by Sappho’s poem?