The Informal Anarchist Federation uses a similar model that your question suggests. The interpretation of federation has gotten a bad reputation because of several attempts to make highly organized anarchist federations has occurred. Often many use "network" instead of "federation" to describe clusters of affinity groups united in some manner.
Your question is underlined with a desire for collaboration on a semi-formal basis. Perhaps you want to see these affinity groups not just have unity through shared documents, but perhaps also annual meetings, shared strategies or something along that manner? Certainly anything is possible. How affinity group is defined in the late 20th century make come initially from Spain, as suggested, but the resurgence of use comes from Up Against the Wall Motherfucker, which defines the affinity group as a street gang with analysis.
What seems to help define an affinity group is analysis of what is going on and by acting on that analysis. If an affinity group's point of view is compatible enough with other affinity group's points of view, then the ability to become a federation might be there.
The platform, when removed of its old analysis and taken only for its reasons of unity has: theoretical and tactical unity leading to the creation of a federation. The point on collective responsibility is more about recognizing that individual actions done in the name of the group reflects how the group is perceived, so should be done responsibly.
This part of the platform need not be reserved to the ideology of platformist anarchist communism. One could take these points and apply them to synthesis federations, insurrectionary anarchist federations, syndicalist federations and so on.
Like platformists would point out also, the theoretic unity and tactical unity need not be tightly defined. An insurrectionary anarchist federation may call for:
- Our enemy is the network of domination as Defined by Wolfi Landstreicher in "Network of Domination".
- To overcome this network of domination, we embrace anarchist projectuality as defined by Wolfi Landstreicher. We will not submit to calls for intermediate gains. We will not work with political organizations.
- We support the tactics of flyposting, graffiti, vandalism and communiques to spread our message.
- While we give solidarity to those that use more extreme tactics, we do not endorse it. Arson and murder are not the tactics of our federation.
- We refuse to work with unions. At work we form workplace committees or workplace fractions that aim to subvert the relationships of workers to work. We are in favor of work abolition.
- In the neighborhood, we refuse to work with government agencies. We will form neighborhood associations or neighborhood fractions that refuse dialogue with the government and law enforcement. We support the formation of municipal assemblies made up of neighborhood associations or fractions that agree to such.
- We support building and space occupations. We support the homeless and itinerants that occupy our municipals and beyond. They are part of our neighborhoods and can participate or refuse to as any others.
- Failing the growth of such groups, we support municipal assemblies of individuals which aim to achieve what goals that can in their given situation.
Something like that.