Here´s my translation
Þá vaknaði hann ok mundi vísuna.
Then he awoke and remembered the-verse.
Jón hét maðr.
[There] was a person (man) called Jón
Hann var Þorsteinsson.
He was Þorsteinn’s-son
Hann var húskarl á þeim bæ, er á Kúlu heitir.
He was a man-servant at that farm, which is-called ‘at Kúla’ (‘Knob’)
Þar bjó sá maðr, er Kjartan hét.
There dwelt that person (man), who was-called Kjartan.
Maðr hét Símon.
[There] was a person (man) called Símon.
Hann var Bjarnason.
He was Bjarni’s-son
Hann var heimamaðr Hrafns á Eyri.
He was one-of-the-household of Hrafn at Eyrr.
Símon átti barn ok byrgiskonu á Kúlu.
Símon had a child (sg, children would be <börn>) and concubine (‘kept-woman’?) at Kúla.
Jón fífldist at þeiri konu.
Jón was-seduced by that woman.
Einn helgan dag fór Símon til fundar við fylgjukonu sína ok sat á tali við hana, en Jón gekk at honum ok hjó hann banahögg.
One holy day Símon journeyed to a meeting with (ie to see) his mistress (concubine) and sat in conversation with her, but (and) John went at (ie attacked) him and smote him a death-blow.
Fyrir þat víg gerði Hrafn Jón sekjan skógarmann.
For that slaying Hrafn made Jón a convicted outlaw.
Nökkuru síðar færði Jón Hrafni höfuð sitt, en Hrafn gaf Jóni upp höfuðit, en hann þakkaði Hrafni höfuðit ok launaði illu illt höfuð, sem síðan mun sagt verða.
Somewhat later Jón surrendered (surrendered his person, lit: conveyed his head) to Hrafn, but Hrafn ‘undid-the-surrender’ (lit: gave up the head) to Jón, and he (ie Jón) thanked Hrafn for giving-him-back-personal-control (lit: the-head) and rewarded badly the bad-‘unsurrendering’ (lit: [the] bad head), as later will become said. (ie as shall be explained later)
Hrafn bætti síðan fé fyrir víg Símonar frændum hans ok færði sjálfr fram sýknu hans.
Hrafn after-that paid weregild for [the] slaying of Símon (gen sg) to his (símon’s) kinsmen (dative plural), and [Hrafn] himself brought forward (ie produced) the-charge (variant of <sök> + def art?) (ie he was both prosecution and (little or no) defence in the case).
15. Atför Þorvalds við Hrafn.
[The] attack of Þorvaldr against Hrafn.
Þat var eitt vár, at Þorvaldr fór með fjölmenni norðan ór Ísafirði til Arnarfjarðar, ok er þeir kómu ofan á heiðarbrún í Arnarfjarðarbotni, þá sá sú kona för þeira, er Ástríðr hét.
That was one spring, that Þorvaldr journeyed with many-people from-the-north (ie south) out-of Ísafjörðr to Arnarfjörðr, and when they came down to [the] edge-of-[the]-heath into Arnarfjarðarbotn ([the] head of Arnarfjörðr), then that woman, who was-called Ástríðr, saw their journey.
Hon var Gunnarsdóttir, Bárðarsonar, bræðrunga Hrafns.
She was [the] daughter-of-Gunnarr, son-of-Bárðr, male-first-cousin of Hrafn.
Hon bjó at Borg.
She dwelt at Borg
Ok er hon sá för margra manna saman, þá sendi hon son sinn út á Eyri til fundar við Hrafn at segja honum mannaferð.
And when she saw [the] journey of many persons (men) together, then she sent her son out to Eyrr to a meeting with (ie to see) Hrafn to say (relate) to him the passage-of-people.
Ok er Hrafn spurði þetta, þá sendi hann menn til Selárdals, at Ragnheiðarsynir kæmi til fulltings við hann með svá marga menn sem þeir fengi til, ok þeir söfnuðu at sér mönnum ok flotuðu skipum.
And when Hrafn was-informed-of this, then he sent persons (men) to Selárdalr, (such) that [the] sons of Ragnheiðr would-come for-the-purpose-of support to him with as many persons (men) as they got, and they gathered to themselves persons (men) and launched ships.
Þorvaldr kom litlu síðar á Eyri en Hrafn hafði sent menn yfir fjörð.
Þorvaldr came to Eyrr a little later than Hrafn had sent persons (men) over [the] fjord.
Þá er Hrafn hafði sanna frétt af ferð Þorvalds, þá bað hann sína menn búast við eftir föngum brennu þeira Ísfirðinga.
Then when Hrafn had a true account of [the] journey of Þorvaldr, then he bade his people (men) to ready-themselves according-to [their] means (<fang>, Z7) for [the] burning (arson attack) of them, [the] folk-of-Ísafjörðr.
Hrafn skipaði mönnum fyrir í húsum með vápnum ok lét vera opnar dyrr allar ok skaut í slám.
Hrafn put persons (men) in charge (<skipa e-m fyrir, Z1) in farm-buildings with weapons and caused all doorways to be opened and (it) thrust into [the] bolts) (I suspect this is an impersonal construction but not sure what it means - the bolts were thrust into place?)
Hrafn hafði boga ok skaut.
Hrafn had a bow and shot [it].
Þorvaldr bar eld at húsum, þegar er hann kom, ok kveikti fyrir þeim durum, er honum þótti minnst vörn fyrir verða, en þeir, er inni váru, báru í vatn ok sýru í eldinn ok slökktu svá sem þeir máttu.
Þorvaldr bore (ie set) fire to [the] farm-buildings, as-soon-as-he came, and lit in-front-of those doorways, where [it] seemed to him to meet (ie that he met) [the] least defence, but (and) those, who were inside, carried in water and sprinkled (sprayed) [it] (variant spelling of <söru>, past tense of <sá>, Z3?) into the-fire, and extinguished such as they could.