agree
I guess the list will even be longer
there are as well state assets, natural resources, financial obligations from rents, state employees, domestic contracts, international trading contracts (with geographically asymetrical cost/benefits), etc.
I think all this is pretty important in peaceful secessions of rich developed nations and there is an abundancy of professionals that do little else as a job in the commercial sector when busy with big Due Diligences, mergers, and splitting of chunks of big companies to sell off.
The way I see it, it is remarkably simple.
Re: "State Assets"
If it is in Catalonia, it goes to Catalonia. Otherwise it remains with remnant Spain.
Re: "Natural Resources"
If it is in Catalonia, they are Catalonian. Otherwise they are Spanish.
Re: "financial obligations from rents"
If government rented building is in Catalonia, then Catalonia takes the liability. Otherise it is remnant Spain.
Re "state employees"
If Catalonian nationals, then Catalonia must take responsibility for employing,transferring or sacking them and paying them and pensions. Otherwise remant Spanish o#ligation.
Re: domestic contracts, and international trading contracts
This is presumably where the central Spanish government is itself the legal contracting party.
In that case you take the agreed population or GDP or combination of such ratio, and
apply it to the national debt and all such arrangements.
Where it may get more complicated is when looking at things such as aeroplanes and ships,
and their allocation and the allocation of support infrastructure which in some cases may not be sufficiently
replicated to be divisible need to be shared for a while with each portion playing a proportionate cost.
EU's job would be to apportion MEP seats, budget contributions and benefits payments.
The key thing is determining the start date and the
ratio.
None of this was a problem in Ireland or India, where the real problem was the boundary.