The word is still friend. In English we use that one word and it covers a lot of nuances in meaning. We know it and we're used to it. It's the context of the language. Do we need a bunch of other words to further break down all the different levels that friend could convey? My thought is no.
Using labels helps too identify and categorize things. As part of that categorization you get separation. Adding in more separation in our society seems a bad thing to me especially around social constructs. If you develop eight different words to replace the usage of friend and all the varying contexts and nuances that it has, what has it gotten you that you didn't already know? What it does is place barriers between you and the people you meet. Now people will be wondering why they are only at friend level 2 instead of friend level 5. Because you put a label on it. Everyone knows the levels of their friends. If you meet someone at a bar and chat with them for an hour and you say have a good evening my friend we know that this is unlikely to be a person that you could call up at 4:00 a.m. because your house is on fire and you need a place to stay. We don't really need nuanced words to describe it. All of this kind of thinking separates people and promotes social competition in an unhealthy way. Ultimately the labeling someone as a friend level that they don't believe they are could cause you to lose them entirely.
The depth of friendships are known by actions and we should leave it as such.
I just call them friends, I might be lucky but I find that most people don't have enough friends and are appreciative if you 'overstep' that boundary in a non demanding way.
I've used familiar stranger for the people I recognize but don't know, like the people who take the metro or go to the coffee shop at the same time as me.that might not apply.
Using labels helps too identify and categorize things. As part of that categorization you get separation. Adding in more separation in our society seems a bad thing to me especially around social constructs. If you develop eight different words to replace the usage of friend and all the varying contexts and nuances that it has, what has it gotten you that you didn't already know? What it does is place barriers between you and the people you meet. Now people will be wondering why they are only at friend level 2 instead of friend level 5. Because you put a label on it. Everyone knows the levels of their friends. If you meet someone at a bar and chat with them for an hour and you say have a good evening my friend we know that this is unlikely to be a person that you could call up at 4:00 a.m. because your house is on fire and you need a place to stay. We don't really need nuanced words to describe it. All of this kind of thinking separates people and promotes social competition in an unhealthy way. Ultimately the labeling someone as a friend level that they don't believe they are could cause you to lose them entirely.
The depth of friendships are known by actions and we should leave it as such.