Historically the idea of going and mirroring people's bodylanguage comes from NLP. Formulated roughly 20 years before someone in psychology got around to testing it. The idea might even be older and was popularized in NLP. In therapy context it makes sense.
At the start people like pickup people like Ross Jeffries who preached speech seduction used NLP ideas like that. After a lot of practice and trying different things the pickup crowd came to the conclusion that it's a bad idea to mimick the body language of a girl that one wants to seduce.
The girl might like the guy because he's a good listener but she's not interested on a sexual level. Pickup people than speak about how nice guys don't get laid but end up in the friend zone. In not saying that everyone should take the pickup paradigm as his default roadmap to social interaction, but be aware what you are doing.
Context is important for communication. If you simply want to be accepted into a group than using bodylanguage that shows that you follow others in the group is alright. If you go into a job interview signaling that the person you are talking to is the boss makes sense. Different rules apply when you want to be a leader.
Looking at body language from a perspective of a study like the one you point towards that misses the point of language. We use language to react differently in different situations. The idea of walking around and constantly saying: "I'm confident. I'm confident" would be silly.
Because if you are mimicking confident body language effectively, you should begin to both feel and look confident.
If your mental attention is on mimicking body language I think there's a fairly good chance that you won't feel completely confident. If you already feel confident, why mimick the body language of another person to make them like you? The high status person doesn't need to change his body language to make the other person like them but rather wait for the other person to change their body language to their own.
Expecially for someone not used to it, it will also drain a lot of attention that's better used elsewhere. If you want to be a good listener I wouldn't recommend to focus on mirroring but on putting your attention on where feelings arise in your body in reaction to the words you are hearing.
If the words of the person I'm speaking with touch my heart I might even put my hand on my heart to be more present to the feeling.
I searched a bit on google studies but couldn't find any that investigated the issue of status effects of mimicking. Reading studies can be useful, but it's important to be aware of the questions that are asked.
I think the key to understanding body language is to actually practice. Be aware of what people around you and yourself do with their bodies.
There was a post (which I unfortunately couldn't locate) that argued that rationalists should aspire to more - that a successful rationalist should be able to master other skills too that make it obvious that being a "rationality master" is something to aspire to.
Several skills such as writing, speech craft and social skills are different from more procedural skills in that they are best learned by observational learning. Strong logic skills don't provide the same advantages here that they do in maths or science - in fact an intermediate level of logic is often a disadvantage as it leads to expecting other people to behave logically.
So if we wish to develop these skills as a community, we would need to develop a repository of examples with notes to explain what principles each example is intended to show. There might be some disagreement as to how applicable each principle is and whether a particular decision is correct - but it would still be far, far better than what else is out there. Unfortunately most communities on the Internet (ie. reddit.com/r/socialskills) end up with huge amounts of rather general advice. This advice is helpful in the beginning, but you quickly get to a stage where you have heard all of it before many, many times. But with examples, even people who are extremely talented may get something out of it.