I think the notion that "loi nanmu cu bevri le pipno" is a legitimate transform of "lu'o ci lo nanmu cu bevri le pipno" is no good. In the latter sentence, there are only three men involved, even if there is no telling which; but in the former, all human beings are conceptually if not actually involved. The two sentence have the same truth conditions, doubtless, but not the same semantics. Paedagogically, I think that this is not the way to introduce loi at all, though it works well for lei. Instead, it would be better to create a new scenario involving one of the "creatures of loi", Mr. Monkey or Mr. Water or whatever.
What I may do is do {lu'o le > lei}, which is straightforward, then {lu'o lo > loi} with a disclaimer, then tack on Mr Rabbit on the end as an alternative way of looking at things --- maybe as a note.
Answer to exercise 3.7: prami > nelci (the exercise says "likes", not "loves")
Maybe change the phrasing of "[...]read as vo ki'o musore. ki'o also has the[...]" to prevent misreading "vo ki'o musore. ki'o" as 4,592,000.
s/harrassed/harassed/ Or is this a Commonwealth spelling?
The example of ungrammatical German der Frau is a bad example; this is perfectly valid grammar, as long as you're referring to the woman in the genitive (das Buch der Frau = le cukta po le ninmu) or the dative (Ich gebe der Frau das Buch = mi dunda fi le ninmu fe le cukta) case. I suggest changing it to something else such as das Frau or die Mann.
In the same spot, 'the two womans' is fine in English, except that the plural of woman is 'women', not 'womans'. 'the two woman', however, is as bad grammatically as 'more better' (which should be 'even better') or 'I gots the ball' (to indicate the ball was 'gotten' (another bad example) in the past).