Throughout this response, I use "qualia" rather than "quale" at some points because there may be more than one quale associated with that thing, I do not want to assume.
> "Is that very different from "I like elephants", "elephants are beautiful animals"?"
Yes, at least from a technical standpoint in Lojban. In Lojban "lo xunre" is a red thing. So, we can only say "I like red things" and "red things are beautiful things". To actually capture the essence of redness, we need a new mechanism. We could also use it in order to capture the qualia of elephantness, but that is only sort of what you probably like or find beautiful. There is an added layer of abstraction or instant-experience there. Red (the color) is a sensation, independent of what is causing it (the stimulus). The essence/being of an elephant is similar, but not really a sensation that I, at least, directly register normally. However, if you had never seen an elephant and I described everything about them to you, and then you eventually experienced one in real life, any new information that you gained from the experience would presumably be the qualia of elephantness and that is something which you would have a firmer grasp on and might like. I would not say, though, that most people are thinking this way when saying that they like elephants, although maybe they could or should (or should could).
> "Is that very different from "I see elephants" when there are no elephants around?"
Again, a little bit. Seeing red is a direct sensation. There is no object involved and no processing/deeper understanding. Seeing an elephant is seeing an object which is an elephant and interpreting it as such (even if that object does not exist, there is no way of knowing that by instanteous vision alone). Of course, there are some qualia to it, but there is also, in the normal interpretation of that statement, something more. It is not impossible to see the qualia of elephantness, but that is not what you really mean, I think.
> "So "I like elephants" becomes "mi nelci lo ganseti be lo ka xanto"?"
No. That is "I like the qualia of elephantness". Liking the object of an or several elephant(s) is just "mi nelci lo xanto". An elephant is one object which has the qualia of elephantness (and, arguably, might be the unique class with this property). Analogously, "mi nelci lo xunre" is "I like one or several objects which are red". These objects are things which have the quale of redness (possibly and even probably/arguably necessarily among other qualia). To like redness itself, the very idea and essence and immediate sensation of it, one needs the qualia abstraction.
> "I don't see a problem with a word for "qualia", but I don't expect people to start saying "I like the qualia of being red" or "I like the qualia of being an elephant" instead of "I like red" or "I like elephants" though. It seems more natural that "lo xanto", "lo xunre" can be elephants (in general) and red as well as particular elephants or particular red objects. I'd rather these ontological distinctions be handled with brivla, not grammaticized with cmavo."
It is a matter of what people should say, not what they currently do say due to bad habits and the failings of natural languages and their own education and tendencies in using Lojban. If they are alerted to such issues, then they are more likely to improve. As they currently are, and if they ignore these issues, they are incorrect. Lojban is, in my opinion, meant to bring this realization to the surface and then to fix it and to provide the tools for doing so in a reasonable but uncompromisingly rigorous way. Natural usage has nothing to do with it because it is wrong in this case.
I think that a cmavo is extremely beneficial and probably necessary in this case. In general, we may try to avoid staking out ontological positions via their establishment.
Note that this is not just a philosophical position that is being hardcoded into the language's vocabulary, functionality/support, and grammar. There is already a major flaw in the language that must be patched somehow. This is one solution, and a versatile and robust one at that. And, like I said, it is good to bring awareness to the language's learners about this issue in their own conscious understanding of their cognition.