The author never really defines "consistency" anyway. Consistency of what?

I've never seen consistency of libraries and even programming languages have a negative impact. Conversely, the situation you describe, or even going out of the way to use $next_lang entirely, is almost always a bad idea.

The consistency of where to place your braces is important within a given code base and teams working on it, but not that important across them, because each one is internally consistent. Conversely, two code bases and teams using two DBs that solve the same problem is likely not a good idea because now you have two types of DBs to maintain. Also, if one team solves a DB-specific problem, say, a performance issue, it might not be obvious how the other team might be able to pick up the results of that work and benefit from it.

So I don't know. I think the answer depends on how you define "consistency", which OP hasn't done very well.