How to list UK audition experience on a resume form?
I recently took an audition for a UK orchestra, and am unsure how to translate the experience to US audition format for a resume form. Would appreciate any advice from those familiar with the process!
The audition comprised two rounds, with the expectation they would offer whatever number of trials after the second round. And those trials could go on for months or years.
I submitted my resume, and I was shortlisted. Yay! I was invited to the first round, where there were ~35 candidates. However, I did not advance to the second round.
Translating this to a US form-- Should this functionally be viewed as not making it out of prelims? Or is it somewhere between prelims and semis? Or semis? I understand it was a relatively small invite list, so I was happy to make that cut at least.

You are correct, functionally it should be viewed as not having made it out of prelims.
Typical US auditions will follow this format:
1) Resume/Application submission
1.5) Prescreening Recording submission
2) Preliminary Round
3) Semifinal Round
4) Final Round
5) Superfinal Round
At the conclusion of the audition there are several possible results: one or more candidates will be offered a position in the orchestra outright; they may be offered a trial, which means they’ll come play with the orchestra for one or more weeks before a hiring decision is made; or nobody will be offered a position nor a trial, resulting in a “no hire”, after which the orchestra will hold the audition again in the future.
That said, there are a few small differences in some procedures, usually based on orchestras’ schedules or specific needs for a particular audition.
For example, most orchestras will not require a prescreening submission, and will invite most (if not all) candidates who submitted an application. Some orchestras, due to having a massive pool of candidates, opt to make their prelims a recorded round, after which they invite candidates to a live semifinal round. Other orchestras will skip the semifinal round altogether, and candidates who advance from prelims go straight to finals. Having a superfinal round used to be rarer, but seems to be a more common practice nowadays.
I will also add, for most orchestral resumes, the committee is looking for a very general “Does this person have experience with a professional ensemble: Yes/No”. With more and more auditions being fully screened, your education, who you’ve played for, competition results, etc. don’t matter nearly as much as how you sound in the audition and subsequently how well you work with and get along with your colleagues.