I think "significant adults" is the sociological jargon term we want here.

Bill's suggestion of "role models" makes obvious sense, and as Onidia has pointed out, it is consistent with the dictionary definition of "referente": adults who constitute points of reference for children. Some uses of "adultos referentes" seem to fit this perfectly; for example:

"BUSCANDO ADULTOS REFERENTES. ¿Dónde están. los adultos referentes,. que educan con el ejemplo. y se quieren imitar?"
http://pedagogiasi.blogspot.com.es/2012/09/buscando-adultos-...

But others suggest that the term is a bit broader than that. As here for example:

"Algunos niños presentan faltas reiteradas al control. Cuando se produce una inasistencia, se contacta a la familia telefónicamente y/o se la visita en su domicilio. [...]
Se entrevista a los adultos referentes de niños/as que presentan inasistencias y a técnicos y profesionales de los mismos servicios [...]"
http://www.convencionsalud2012.sld.cu/index.php/convencionsa...

This sounds more like "responsible adults". So does this:

"chicos en situación de calle
Programa de atención integral para hijos de cartoneros [...]
Para acceder, deben presentar los adultos referentes la inscripción al Registro del Programa de Recuperadores Urbanos, así como el DNI del menor y de dicho adulto."
http://www.buenosaires.gob.ar/areas/des_social/niniez_adoles...

I think the term that covers all this is "significant adults":

"ENGAGING THE CHILD, FAMILY, AND SIGNIFICANT ADULTS
Family engagement is partnering with the family to make well-informed decisions about their child’s safety, permanent home, lifelong connections, and well-being. It involves engaging the child’s birth parents, prior custodians, and family members, as well as other community members and adults who are significant to the child and family, consistent with the child’s best interests. [...]
Family engagement involves notifying relatives that the child is or will be placed in foster care, searching for extended family and community networks, aggressively pursuing leads, discussing roles and resources the family members and significant adults can provide, engaging them in the child’s life, and establishing permanent supports and lifelong connections for the child."
http://www.dss.virginia.gov/files/division/dfs/fc/intro_page...

"New research highlights the importance of 'significant adults' in the lives of children and young people in conflict with the law."
http://www.iprt.ie/contents/2458

"Adolescents' perceptions of significant adults: Implications for the Family, the School and Youth Serving Agencies"
http://www.sciencedirect.com/science/article/pii/01907409869...

--------------------------------------------------
Note added at 54 mins (2013-07-19 17:47:25 GMT)
--------------------------------------------------

Actually, in this context "adults who are significant to children", as in the document from Virginia Social Services", might be the right formulation.