"Look at the students"
the singular vs plural directive should be indicated in the english; thus, (you all) look at the students = angalieni, vs. (you singular) look at the students = angalia. adding a subject prefix would also change the suffix: mangalieni (pl.) and uangalie (sing.), as well as change the meaning to make it a polite request rather than an order
Hmm, the way I've seen it used, the -eni is only used on the direct imperative:
angalia > angalieni
And in situations where the object is plural you.
ninawapenda (I love them) > ninawapendeni I love you all.
With the polite imperative (subjunctive), the subject prefix is there, just like almost any other verb form.
uangalie > mwangalie
I'm not saying it's expressly wrong, but I haven't seen the -(e)ni suffix used with the polite imperative.
Mwangalieni to me looks like the direct imperative plural "Look at him/her!", with the "Mw-" appearing as an object prefix rather than a subject prefix.