What do PhD admission officers look for when evaluating an undergraduate thesis? (CS) Background:

Undergrad CS Student (Junior year)
I have a few problem statements in mind for my undergrad thesis.

I have 2 semi-novel ideas (extension works) and 1 novel Idea for my undergrad thesis. All 3 will be separate chapters. I mostly won't be able to complete my experimentation for the novel idea before sending out my applications (for PhD CS in The US) and the other 2 will likely be only accepted in b-tier conferences.
Main question: Is that okay for an undergrad thesis? Do doctoral admissions committees expect only tier-1 conference work?
Other notes:

All 3 papers, I am the first author but there will be 3 other authors.
It only indirectly aligns with my interests which ill will be mentioning in my SOP for the PhD Application.
I have done (and am doing) other major projects. The sole purpose of this work was to carry forward with my interest.
I think that significant research at the undergraduate level is pretty rare, especially if it can be completed and published.
The problem is that there is seldom time enough to get the needed background and also follow up to completion on a significant problem. Research is really open ended, especially in time. It is why some doctoral students take much longer than others to complete.
If you are diving into the unknown on a research question then it is impossible to foretell where or when you will wind up.
For that reason, I think that pretty much any research experience at the undergraduate level will impress a doctoral admissions committee in the US. This would even be true if there are no publication (yet) but perhaps many interesting questions still to be answered.
What is acceptable to your own institution is, of course, up to them, but I doubt, given what you say, that you are likely to leave too many admissions folks unimpressed.