Sir Tristram: Tristran is the hero of Tristan and Iseult, introducing the theme of the two lovers. Also referencing the Earl of Tristram, lord of Howth Castle from the prior paragraph:
https://en.wikipedia.org/wiki/Earl_of_Howth,
https://en.wikipedia.org/wiki/Tristanthe short sea: the English Channel
North Amorica: North America
penisolate: combination of pen, peninsula, penis, and isolated
topsawyer: Tom Sawyer, an American character written by Mark Twain. Also, for lumbermen, the top sawyer stands above log, while the bottom sawyer stands below the log, introducing the theme of a sibling rivalry.
Oconee: There's a river Oconee that flows through Lauren County, Georgia, and the county seat of Dublin: https://en.wikipedia.org/wiki/Dublin,_Georgia
Laurens County: during the Anglo-Norman conquest, the archbishop of Dublin was Lawrence O'Toole; Dublin would be "Lawrence's County": https://en.wikipedia.org/wiki/Lorcán_Ua_Tuathail. Also, the Earl of Tristram changed his family name to Lawrence (https://en.wikipedia.org/wiki/Earl_of_Howth)
doublin their mumper: doubling their number
thuartpeatrick: Saint Patrick. 'taufen' is German for baptize. Peat symbolizes Ireland. The fire references the miracle of Saint Patrick's Purgatory, where he drew a circle on the ground and the earth opened in flame.
kidscad ... isaac: the Old Testament story where Jacob, in rivalry with his brother Esau, disguises himself with a lambskin, to steal the blessing of their dying father Isaac. "not yet, but very soon after, Jacob, disguised in the kidskin, duped blind old Isaac". This reinforces the theme of sibling rivalry. Also a reference to https://en.wikipedia.org/wiki/Isaac_Butt.
Vanessy ... twone nathandjoe: two/one, nathandjoe is Nathan and Joe, another sibling rivalry. Also, an anagram for Jonathan (Swift): https://en.wikipedia.org/wiki/Cadenus_and_Vanessa
sosie sesthers wroth: transformations of Susie/Susannah, Esther, Ruth, the heroines of Biblical stories.
In vanessy: Inverness was the castle from Macbeth.
Pa's malt, Jhem, Shen: the Biblical story of Noah getting drunk and discovered by his sons, Shem, Japhet, and Ham: https://en.wikipedia.org/wiki/Drunkenness_of_Noah. This introduces the theme of the fading of the father into the sibling rivalry.
Yeah, it's dense stuff, but I find it fascinating. This paragraph is introducing a bunch of themes that are explored in depth throughout the book. It's impossible to get much meaning without a guidebook; I've used A Skeleton Key by Joseph Campbell.