Sorry just seeing a bunch of this now, but for anyone asking about the TS cover letter length, I wrote exactly 1,000 words and made it past their application round pretty okay, I think. I do think I remember them saying in an event or on their socials or something that you don't need to write much, and like focus on being concise and relevant, like 750 words should be fine (and makes their lives easier). but I know that me and other people did 1,000 and were chill
Disclaimer, don't listen to me and trust your gut!! I hope that helps, and good luck with submitting < 3 you've got this!!