The first comma is inside an introductory prepositional phrase. The second comma ends this phrase.
There is a three-element coordination. The elements are "the food is served on time", "the waiters work well together", and "hospitality increases". The entire coordination belongs to the word "where", which your framework might label as a preposition, a subordinating conjunction, a relative adverb, or who knows what else.
1) The first comma separates the first two elements of the coordination. An optional comma could be placed in front of "and".
2) There is an introductory phrase: "at the restaurant where [these three things happen]". This is a long and complex phrase, so I have to strongly recommend using the comma that follows it, even if your framework considers that comma to be optional.
The first sentence is a compound sentence. There could have been a comma between the two independent clauses. Certain old-fashioned prescriptive grammars describe this as a required comma. Today, like the Oxford comma, this comma seems to be more a question of style.
3) The next comma follows the introductory adverb "conversely". Not only is this adverb introductory, it is supplemental. It doesn't modify any element within the following clauses, but rather modifies the rest of the sentence as a whole.
4) There is another coordination of three elements: "the food is not served on time", "relationships therein are strained", and "arguments occur". Once again, elements that are not joined by a conjunction are necessarily separated by a comma.
5) The phrase "at the restaurant where [three contrasting things happen]" is another long and complex introductory phrase.
We know that the two coordinations which are the objects of the words "which" are three-element coordinations because the coordinate conjunctions come before the third elements. Similarly, we know that the compound sentences each contain two clauses because the coordinating conjunctions appear between pairs of clauses.
Because the coordination of independent clauses in both compound sentences happens to be shorter and simpler than the introductory prepositional phrases which modify them, the lack of commas between clauses is the style that I prefer.
The three-element coordinations also contain complete clauses. I would label them as subordinate clauses and label each "where" as a preposition that takes a coordination of subordinate clauses as its object. The reasons I find the lack of a comma before these coordinating conjunctions to be better style are that there is no stronger punctuation available to end the introductory phrase and that the three-element coordinations are subordinate to the phrases which employs them.