First off, very interesting TL, keep it up.
The Celts are something that are near and dear to my heart so forgive this bit of nitpick. I think it was around 500BC you had several tribes join Tartessos without a fight (unless I missed something) – why? Wouldn’t the rest of the Celtic nation have something to say about this? I think I would have given the forest green a little more territory into what you have marked as Nordica as the migrations out of that region would have only just begun due to the changing climate (but this isn’t my TL so who cares what I would do really). It wasn’t really until the 3rd century BC that you have the more northern tribes like the Suebi, Teutonii, Marcomonii, etc. coming into what had been Boii lands.