Is there a way to check this ID when dealing with the Record? I want to check his form, but I don't want to rely on the Internal ID, but this one

I think you can only set

customform

with that value; I don't know a way to read it in script (i.e. only the numeric internal id)

Yeah... Only way I can think to handle something like that is a mapping file. Like

{custform_compensation_order : 112}

but that would need to be maintained.