Thanks to Andrew for his points and to Marko for his counterpoints.
I think the concept of Provencal and the few northern footholds of Christian Iberia being originally a single somewhat nebulous Tribunal makes some sense actually, although currently this concept would seem difficult to reconcile with the concept of the Lotharingian Tribunal per canon.
How about this then:
I'd prefer to consider the earlier Iberian Tribunal as a "rump" Tribunal (Marko, don't get offended, hear me out here) - a smattering of independent covenants aligned to no Tribunal and predominantly Flambeau eremites, not officially belonging to a Tribunal in the official sense, centred around or populated from Val-Negra initially - hence the somewhat grandiose title: "Tribunal of Val-Negra", even if gatherings of these covenants do not constitute an official Tribunal. Local Quaesitor rule becomes difficult to enforce but Grand Tribunal rulings would still hold in such an environment however - although how far the Order would care to enforce things in "backwater" Iberia would be debatable.
If Hermetic activity follows the basic outlines of Christian holdings in history (and I'm not completely convinced that this should be the case for a number of reasons), then the amount of territory belonging to such a putative Tribunal would be pretty small even until the latter half of the 11th century where the Northern "Spanish" kingdoms don't extend past the Tagus (although Toledo was captured in 1085) and only minor inroads have been made into the Ebro valley. To call the small segment of northern peninsular held by Christian kingdoms up to this time the "Iberian" Tribunal is a bit of a stretch IMO, even for the Romanocentric Order, regardless of the number of covenants.
Perhaps as Hermetic political borders take harder shape in the 10th and 11th centuries per canon (such as the formal declaration of a border between Normandy and Provencal in 1050 and the loss of Gascony from Normandy about the same time), such independent covenants began to coalesce into a nascent Tribunal - particularly after the migration of House Flambeau from Normandy around 1065 in the wake of the Perthean Compact's effect and the rise to dominance of House Tytalus in NW France (note Fudarus joins Normandy only after the Schism War, previously belonging to the Brittanian Tribunal). Even in the old ToH: Iberia book, Barcelona, which dominates most of the supplement, is only established in 1014, after the Schism War, and given it's Catalan background seems to make more sense as a Catalan magi incursion from Provencal to me. From reading Lion & the Lily it seems a fair proportion of House Flambeau's attention was directed northwards into Normandy - only after the Perthean Compact does the focus seem to turn away and at the time historically the eastern Crusades and the Reconquista would seme likely to grab their attention.
This view would make the putative founding of an Iberian Tribunal quite late make sense - after the Schism War, the extent to which Iberia is involved has always been unclear in previous canon, making it in effect a "young" Tribunal. Hermetic settlement precedes formal recognition as a Tribunal in all cases anyway - perhaps Iberia is just an extreme example, being recognised "officially" over 200 years after the initial Hermetic footholds, having been quietly ignored by polite Hermetic society until that point.
In fact, not actually having an "official" Tribunal in Iberia until post-Schism War and the joining of the sahir to Ex Miscellanea in 925 could go a long way to explaining some of the seemingly unsanctioned lawlessness of the area in previous visions of Iberia and allowing the elements Marko is so fond of remain, even if they are at odds with some of the revised concepts of Flambeau in ArM5. Covenants such as Estancia es Karida (founded 978) and other Muslim Hermetic covenants or independent Andalusian Jerbiton or Criamon covenants would seem to fit better into this scheme than any other - I find it quite hard to picture a peninsular wide official Tribunal making a lot of sense in light of these concepts.
This way, we could have the old-style Flambeau playground history in "wild-west" Iberia, just beyond the reach of the main body of the Order (and out of sight, out of mind over the Pyrenees as far as the rest of the Order is concerned - much like Iberia during most of the early Middle Ages), but then layer on top the more refined later Flambeau culture of the Milites of HoH: Societas and the Catalan Jerbiton magi of Barcelona that are central in concept to the old ToH: Iberia book (minus a few of the demons IMO though).
I think there's a lot of potential this way - retain the old style Flambeau history loved by many, but allow the flexibility of play and diversity of Hermetic culture to seep in during the later history.
Thoughts?
Lachie