Yep, but it is still a huge amount if Alien X has a life-span of 25,000 years -- is able to continually push the edge of THEIR own singularity factors -- have been "lucky enough" to receive more than 5 senses through whatever local evolutionary mutations -- can actually travel beyond FTL -- are coming from our past or will develop faster than us in our future -- mastered intra-dimensional accessibility... etc.
As for this, anything that can be known will be known by any post singularity society, limited (possibly) by the kinds of factors I described above. Lifespan has nothing to do with it.. this isn't about individuals, but species and beyond that life (or evolving matter) itself. FTL travel will be known by any post singularity society.. there is no "barrier to push", only "before knowing everything" (pre singularity) and after knowing everything (post singularity). The period of "pushing the boundary" takes place just prior to singularity and occurs over an extremely short period.. humanity's period is likely to last 10,000 to 15,000 years as I said before, and it is nearly over. "Senses" are a misnomer to begin with, as they allow us insight into the phenomenological world. That is to say, there is a noumenological world that creates observable phenomena, and our senses allow us to percieve those phenomena. The only kinds of life that could exist outside of the phenomenological universe would have to exist in some location that has absolutely zero interaction with any matter or energy in our phenomenological universe. Otherwise, knowledge about those interactions would be studied and understood by a post singularity society (dark matter is a good example of a weakly interacting phenomena.. matter that appears to interact with other matter based only on gravitational influence). We can study those weak interactions and learn all that there is possible to know about dark matter from our vantage point in the universe. Likewise, if there is some matter and energy in the universe that is undetectable "dark matter and energy," any beings made of that matter would be limited by their vantage point in the universe and only be able to observe interactions with normal matter through gravity. Further, it is only possible to understand phenomena scientifically. Noumena are inscrutible and have the potential to create new or different phenomena at any time.
To put it in simpler terms, the way we observe the universe is like looking at ripples on water. We can observe patterns in the ripples, identify their origin, and learn how they interact with each other. We can predict what happens when two ripples collide, and we can have a very solid understanding of the pond we are looking at based on those ripples. However, we never can see what is causing the ripples.. is it raining? Are rocks being thrown into the water? The ripples are phenomenological in this example, the causes are noumenological. The "thing in itself" cannot be known, and as such it can create phenomena not yet observed or predicted. Many, many philosophers have addressed this issue.
In any case, senses let us observe the phenomenological. Post singularity societies will understand all phenomena completely, regardless of what senses they started with. We already observe much that was outside of our phenomenological realm only decades ago.. the electromagnetic spectrum beyond visible light for example. Any pehenomena that interacts at all with the observable phenomenological universe will in turn be observed, studied, and known. Anything phenomena that does not interact at all with our phenomenological universe will never be known and, by definition, will never interact with us. No "aliens from an alternate dimension" or anything like that.. if there is an "alternate dimension" that is accessible by us, as a post singularity society we will know it and have as much access to it as is possible. Same thing goes for time travel. More or less, all post singularity societies know exactly the same things and have access to exactly the same technology... that is, everything that can be known and everything that can be done. With limits again as I described above.