Resolving dependency on a senior colleague before deadline (Disclaimer: While this question pertains to interpersonal issues in a working environment, I feel it is better suited to this SE than Workplace because of it being in the context of a lack of formal responsibility/hierarchy in an academic environment)

Background

The deadline for the camera-ready version of a publication and conference registration is in seven days; In order to finalize the publication, I need to specify information regarding licensing of the primary data (it is literally an HTML field which I have to fill out in order to submit the paper; It is not "just" some legal requirement).

I do not have the experience to decide what licensing is applicable to the type of data I need to license, the hosting setup for the data which will ultimately be in place, and the country/countries involved (I don't even know what countries would have jurisdiction). However, this would in theory not be a problem, because a tenured member of staff, who also said they would settle the issues regarding hosting, said they would "look into it". This person is otherwise not related to the publication or project.

Problem

The problem now is that I have been regularly asking the person who offered to deal with licensing issues about the status of the issue for two months now, with the frequency and seriousness of the contact increasing (first it was an occasional e-mail, then more e-mails, then physically finding said person and asking them in person). However, now I have almost no time left, and I still have no resolution to the issues described above. 

I do not doubt the person's "trustworthiness" since they are a senior member of faculty in a small department and I know neither this department nor the person very well. Nevertheless, I cannot trust that this person will magically do what I asked of them one hour before the deadline because the stakes are too high. How can I resolve my dependency on this person before the hard deadline, i.e. how can I get them to do what they said they would do when I cannot do it myself and don't have time to find someone else who can? The person is neither my supervisor nor formally part of any project I am working on, so I have absolutely no way of formally resolving this.
Circumvent that person as a stop-gap. Specifically:


Fix a time shortly before the deadline when you are certain you'll be able to make the submission setting the information yourself.
Guesstimate to the best of your ability what the correct value for the licensing field should be - erring on the side of making data openly available (i.e. something like CC-BY-SA or public domain).
Regardless of how you communicate with the person who's supposed to take care of it - when the time comes, if s/he hasn't done it, you do it.


If that person gets upset after you've applied this stop-gap - you'll be able to argue that it was necessary so as not to miss the deadline, and that you're sorry but you had no choice. You can also say that if s/he believes somethinh else should have been put in, you both can always communicate the change to the organizers and say the original input was an error.

As for an effective way to "prod" this person, I can't suggest something particularly great without additional information, but:


You could talk to someone who's in close contact with him/her, and on speaking terms with you, and get them to try to apply their influence.
You could bring this up in a public forum where s/he is also participating, e.g. a group status meeting.
You could let him/her know about your stop gap in advance. That's a bit risky because they might object and you may end up having to directly disregard the objection.