"ku" is unnecessary here. And "le" should definitely be "lo" in this case.

Why should {le} definitely be {lo}?

At the time I wrote it, {ku} sounded better... Not so much now.

Because when you're using "vi" as a demonstrative, you really don't want the listener thinking anything weird is going on. The speaker is most likely pointing at the object, or it is the only thing satisfying the predicate that is close to the speaker, so "lo" works fine.

Here is another way of explaining it: Let's say we are talking about a certain apple tree that I saw. I say "An apple fell from the tree.". Obviously, I have a specific apple in mind, but you don't know about it, and it's not that important, so I saw "an" rather than "the" (and I would say "lo plise cu farlu fi lo tricu" in Lojban). Now let's say that instead I had the apple with me and was holding it out in front of me. I say "This apple fell from the tree.". It's the same apple as before. I saw the same thing happen, and I have the same apple in mind. The only difference is that I am now holding it and I say "this apple" to make that clear. English doesn't have articles with demonstratives, but in Lojban, following the same pattern as the non-demonstrative sentence, you would expect to use "lo".

On the other hand, you can just say "ti noi plise" and then nobody can complain. ;-)

(The downside is that then you can't distinguish between inner and outer qualifiers, and it's really hard to make an equivalent of "lo vi mi plise", unless I'm missing something. "ti pe mi noi plise" doesn't work because "noi" applies to "mi", and "ti noi plise [ku'o] pe mi" doesn't work for reasons I don't understand. For these reasons, I don't particularly like this form and generally try to avoid it.)