chápu to dobře, že „It's a fair prospect“ = „It's magnificent view“ :

odpověď je: „Pretty enough, I grant you“ – Opravdu nádherný, souhlasím. :

Book or film?

film, úplný začátek, vyjeli z lesa a dívají se na vzdálený zámeček

Didn't see it, but your interpretations sound about right. „Pretty enough“ might be better translated as „Dost nadherny“ as in „yeah, it's not so bad“…

američanka: Is the word „matrimony“ today used ? Perhaps at church wedding? Česky bych řekla „posvátný svazek manželský“, but I have heard it only during a wedding in a church.

I should never have called on him – Nikdy bych ho nepozval (?) nebo spíše Nenavštívil bych ho, Nezastavil bych se u něho?

We are gathered here today to join these two people in holy matrimony…yes, only in church will you hear that.

„to call on someone“ is to visit them – you would leave a „calling card“ if they weren't home to let them know you'd been to see them – hence the Czech word „vizitka“ („visit card“) 

Lo! (prý zastarale „hle!“ nebo „a vida“)
„call on someone“ is my first phrasal verb in which I can see now any sense Marvelous 

Yay!!!

He slighted poor Lizzy, and flatly refused to stand up with her. (pohrdl L. a kategoricky odmítl s ní tančit)

My new way to learn phrasal verbs:
Is there any connection between „stand up“ and „jít tančit, odolat, nechat čekat a vstát“ :
Perhaps they stood when they dance 

I am surprised that phrasal verbs are in old-fashioned film, maybe they are used since good old times  

• You're severe upon your sex, Miss Bennet. (na to, že jste žena, jste pohotová?)
  • I must speak as I find. (říkám, co si myslím?)

  You must not be so severe upon yourself. – (nemusíš být na sebe tak přísná?)

Last sentence – yes, and go back and apply that to the first sentence
Second sentence – yes

I'm most exceedingly obliged. (Jsem vám nesmírně zavázán? – dostal šek na peníze)

This sentence must be old-fashioned English, isn´t it? Now we can say:
I'm very grateful?

It's a lovely sentence, Jarmi – and yes, it means I'm very grateful or, in other words – thank you very, very much.

I must translate something to up-to-date English

An example:
Only let me assure you that I can, from my heart, most cordially wish you equal felicity in marriage.

(= I wish you happiness in marriage)