Impatience, and a recognition of the pitfalls of "Not Invented Here". So they want to contact us and don't want to wait.
There's one aspect of the Salarians worth noting that could applied to your advanced alien race - they have a shorter life span than a lot of the other aliens races out there. They populate fine, so they're not going to go extinct, but a single alien wanting to meet a new alien race can't wait 1000 years for them to catch up and acclimatize. It's part of, but not the entire reason, that Salarians chose to just uplift Krogan to fight the Rachni, and the Turians to fight the Krogan. They either don't have the time, or don't want to burn the time, doing slow methodological contact with a new alien race, especially if they're finding a bunch of other, unlifted species.
So, they decide to take their universal translators that worked for a bunch of other races after a while, and go to Earth. It doesn't work initially on any languages here, but the easiest way to get it to learn is to be in the field, so...they drop down in France.
Once in France, they learn enough to communicate to the French there, and then walk a little out of the borders East to Germany. Wait - the universal translator has to train again? Well, this is annoying - let's go South - wait, Italy has another language?
Well, this is annoying - let's get to orbit and go somewhere more East. Wait- now we have to do this translation for Mandarin, Cantonese, 3 different alphabets for Japanese texts? This is getting ridiculous - let's go South-West, that seemed promising...or not.
Wait - this language North West of Mandarin and Cantonese is...using glyphs that are similar but mean different things than the ones in France and Germany?
"Hey, so one of these people pointed us towards an page on their 'internet' that translates 108 of their roughly 6,500 languages. We should just hand them our translation technology and help them integrate their existing translation capabilities into our systems, so we can easily talk to them, and they can figure out the implementation details."
Not every alien in their race is going to be Kirrahe and want to hold the line of doing the intelligence work and "Hold The Line" on giving the new alien race more technology than they need to achieve mutual goals. Others are more like Mordin, and prefer to "Get the job done and go home".
You can apply this to a whole suite of problems, but if they ever need to compare what time things happened historically, it'll be easier honestly for them to give us their hardware and software and say "Right - this is how our timelines worked for our planets, this is where we currently are in the timeline in our representation - can you just figure out how to map your things to ours?".
This, of course, ignoring the ways to interface with newer technology, and the variable ways to make it accessible for other humans, that would likely have also come up with other, similarly under-advance alien races. After enough situations, an advanced alien race just says "Right - let's just help them make our tech backwards compatible with theirs, or theirs forward compatible with ours. We don't need to hold up our pride on our particularly specific implementation - we want it to work in 1-2 years, not on the timescales of decades or centuries.".
TL:DR; It's just quicker and easier to let an under-advanced alien race help an advanced alien race interact with them, even if they have to give up dangerous technology to do so.