As you both mentioned, it's not possible to know what will happen being that this credit is fairly new. What we do know now is that the Edit credit is clawed back 1 day after cancelation (at least that's how it was for me and some others here) and it then becomes available for use again.

Being that it's the end of the year and time is of essence, what I would personally do is book again now and then cancel the original booking. This way the Edit credit may not be reversed at all and also your new booking charge will for sure post still in 2025 so that in the case that the 2025 credit is reversed and for some reason not reapplied to the 2025 booking you have a leg to stand on in getting them to honor the credit. I would not wait until the last day or two of December because then the transaction may not post until 1/1 and will then use the 2026 credit which isn't what you want. It happened to me with the CSR Biz and the first half year credit - I made a booking on 6/30 but it posted as 7/1 and used the second half year credit and they wouldn't budge on giving me the first half year credit even though I talked myself blue in the face and sent them my email confirmation dated 6/30 etc.

I hope it works out for you both. Good luck.