[FennNaten]

From what I read, OP did speak up at the beginning to say that backend was late, but never directly put K's methods as the center issue, to avoid 'pointing fingers'.

Even when transferred team members complained, before leaving, OP didn't state in the text that anything was brought up to management.

There are orgs where managers 'above' the team lead level are completely clueless about the technical side, and OP's company seems to be of this type if K's getting away with her behavior, meaning that she can bullshit her way through this if nobody on the same level rises the issue.

Still, I'd agree with getting out of this type of org anyway, but upon reading I just feel like OP didn't 'fight' properly. There are several levels of action that one can take in this situation: trying to influence the coworker's behavior, face to face discussion, documented report of what's wrong to management, asking for an assessment of project state by another experimented tech lead... And these actions have to be taken early on, quitting being the last resort.

Note that I'm bringing this up because I haven't seen these mentioned explicitly in OP's writeup, so I assume that none of these strategies have been tried, but I may be wrong.