Campaign Faction Selection, WIP image - Medieval Kingdoms Total War (Attila Version) mod for Total War: Attila

Looks great!

I want a portuguese campaign so bad!!! Thank you for your effort!

Possible add Galician option?

If I may propose a suggestion, for the National trait, consider the following:
The first bonus, "Portuguese Heavy Ship design" sounds a bit too generic to give Portugal some Naval related bonus. Allow me to give you some historical background on Portuguese shipbuilding:
Somewhere in the early 1200's the Portuguese King Sancho II did order the plantation of a large pine forest, the "Leiria Pine Forest", which was again expanded by Denis I later in the same century, which later served as the main source of wood for the Portuguese Navy in the centuries to come. So, it could be made a case that a Heavy Ship discount bonus is justified, but it could be renamed to: "Leiria Pine Forests" or "abundant pine reserves" or something like that.

The Bolsa do Comércio bonus however makes little sense. The oldest Bolsa do Comércio that i am aware of is a 19th century institution in Porto. This could be a generic bonus to trade, but why? Portugal was never particulary good with trade. Sure there was a brief period when they profited a lot with trade in the mid to late 16th century, but that was due to a monopoly on the Indian spice trade, which is completely out of the scope of this game both geographically and in timeframe.
Medieval Portugal had mostly an agrarian and fishing-based economy, and was rather poor actually. I don't see a need for this bonus.
However, i do see a need for a defensive bonus. Medieval Portugal was exceptionally good at defending its sovereignity from the dominant Iberian powers (usually Leon or Castile), in the 14th century alone it waged 5 wars against its far larger and much more powerful Castilian neighbour and it was either a stalemate or a decisive victory. Some battles during these wars such as Aljubarrota, Atoleiros and Valverde humble the likes of Agincourt and Crecy. I believe a solid +10 Morale in defensive battles is a very fitting bonus for Portugal, as well as making it much harder for Castile to conquer them (since historically Castile always failed their attempts). I would name it "Independence Zeal" which goes perfectly in line with the name of the trait "From County to Conquering Kingdom"

As for the bonus to building conversion... I do see the logic behind it (you don't see nearly as many Islamic buildings left in Portugal compared to Spain) but considering Portugal starts with its Reconquista finished, is it really useful in any way? I guess its useful if you expand in Iberia or North Africa, but if you are aiming for historical accuracy Portugal shouldn't be doing any conquering anymore. So while this bonus is justified i'm thinking a different one might be more suitable. I suggest a +2 experience to crossbow units, this is based on the "Besteiros do Conto" ordinance, which stated that each municipality was forced to mantain a standing force (whose size depended on the number of families living in the municipality) of crossbowmen trained and equiped for war at all times, and could be raised at all times by the Crown.

As for the penalty, i guess it does make sense, Medieval Portuguese armies did have an alarming shortage of Knights (unless considering Holy Orders) and relied far more on peons (usually spearmen).
However I was thinking maybe Portugal could have a morale penalty on offensive sieges, so its harder for them to expand. This is because like i said before, they shouldn't be conquering any further. They should be excellent defensively but sub-optimal offensively. I would maybe name this penalty "Finished Reconquista" as in the lack of incentive to expand further since their holy duty was fulfilled