Hi Davide,
I think it should be possible to emulate this via preemption: if you set PreemptMode to CANCEL, a preempted job will behave just as if it reached the end of its wall time. Then, you can use PreemptExemptTime as your soft wall time limit -- the job will not be preempted before PreemptExemptTime has passed.
See https://slurm.schedmd.com/preempt.html
Best,
A.