The commitment statement agreeing the plan needs to be signed by everyone, obv.
But, if you mean the evidence of those hours, think of it like this: In classroom learning we don’t ask learners to sign in, the register is marked by the tutor and that evidence is deemed acceptable. I suppose the only difference would be evidence of stuff where you don’t have a member of staff present, where you’d want agreement from employer/app that the sessions/hours happened. EVEN THEN, not sure i’d demand wet signatures (not in 2020), email/electronic confirmation should suffice.
Here’s the thing though, if you set a too high threshold for what you accept as evidence, you’re just shooting yourself in the foot because you’ll end up with less than 20% evidence and an auditor will have all the money back.
To my mind, if ESFA are happy with it, that’s sufficient evidence for me!
One could argue that if a provider is working with an employer they don’t trust to do things correctly, then maybe that employer isn’t someone they should be working with…