Venture capital - SAFE and KISS - How to assess FV at YE ?

Hi !

I rencently notice the use of SAFE and KISS instruments by venture capital funds and was wondering how valuators would assess the FV of these instruments at a particular date ?

For example, a SAFE can be converted in regular equity, so where a conversion is foreseen and or imminent, I suppose FV could be the conversion value. But what happens if the company is not doing well ? From my understanding a typical SAFE is not really reimbursable, so what happens during the period where you don't expect to convert but the company's not yet winding down activities?

For KISS instruments, how are these treated ?

Thanks !