Charles Davis Sep 6, 2013:

All that's quite possible... which is really what I meant by saying that there are several things "instancia" could mean. However, in this context I think it is much more likely to mean participants in the collaboration, whether institutions or departments. See for example how the word is used in this Mexican doc. on academic collaboration agreements:

"...deberá contarse con la intervención de la instancia a la que
corresponde la gestión..."
"...para proceder a la firma del documento por las instancias adecuadas..."
"El Director de la Unidad Académica, Departamento o instancia de apoyo..."
"RESPONSABILIDADES DE LAS PERSONAS E INSTANCIAS
INVOLUCRADAS EN LOS CONVENIOS"
"Turnar al Jurídico y a las instancias competentes el documento para su Visto Bueno."
http://www.uia.mx/web/files/0027.pdf

ViBe Sep 6, 2013:

Not necessarily LEVEL or INSTITUTION… … “instancia” could very well imply “line of work” / “area” / “subject matter” the respective working group (WG) / panel of experts would be dealing with.

Along the same lines, “(un) responsable“ could be “focal point” / “point of contact” (POC) / “coordinator” in charge of interaction with his/her opposite number in a particular specialist WG.

Hence: “por instancia” => “per subject,” but the question should have been worded in this fashion: “un (responsable) por instancia,” then we could arrive at: “a POC per WG.”

Charles Davis Sep 6, 2013:

instancia There are several things this word could mean and in my opinion we can't tell which it is without further information about the nature of this collaboration.

Specifically, it quite probably does mean institutions, as Phil suggests, but this tends to imply that there are more than two involved; it would be a bit odd to describe two people as "un grupo permanente de trabajo". Maybe there are two parties to the agreement but others will be involved in the scheme too; "la designación se hará por conducto de los titulares que firman el presente convenio" suggests to me that this may be the case. Can this be confirmed? If it is so, I think the meaning is almost certainly "from each institution".