How are they supposed to be translated? As Mr. and Mrs.?
		
		
	 
There are many ways in English to convey a similar tone to the original honorific. Words like: sir, lord, lady, madam, highness (for royals) can be used in variety of situations to describe relation/closeness and a hierarchy. Kun/chan can be translated/localized to english as a nickname or possibly adding a prefix like saying ‘little Timmy‘ in place of ‘Timmy-kun’. SImilarly, calling someone named Annabelle ‘Annie’ implies close bond between the person Annabelle and the speaker.
This translation  uses ‘Lady Grace’ instead of ‘Grace-Sama‘ and they roughly convey very similar meaning given the context here. Implying a hierarchy, social standing, and respect.
A true one to one translation will never exist between languages as subtle nuances are bound to be lost. But, taking a slightly more heavy handed approach can sometimes convey the right tone (not replacing honorifics, or using nicknames in their place).
Personally, I prefer translations try their best to convey the meanings and context in the target language without relying on readers being familiar with unique nuances of the original language (Japanese or any other), especially when the original work is set in a place unrelated to the original language’s unique system (Japanese style honorifics and social principles applied in a European setting). But I won’t ignore that other in cases keeping them is the right decision (Japan focused plots or folklore, for example).
To each their own preference
As for punctuation, I prefer they be proper as that respects the target language’s grammatical rules. But it’s barely an issue when there are other indicators such as line breaks or sentences being in separate bubbles that clearly indicate the flow of the sentences.