This seems very confusing and open to weird interpretations.
Not as I see it. I wrote this amendment on Sen. MasterJedi's request (although I do not support it). The U.S. Constitution uses almost exactly the same language:
"New States may be admitted by the Congress into this Union."
The language of the proposed amendment, as you can see, is practically identical, except for the change from passive to active voice. It just allows the Senate to admit new states by law, i.e., by statute, just as the U.S. Congress may do now.
The other part of the Amendment allows the Senate to apportion states to regions and districts, subject to the population rules for the latter.