Nice map! But I think that there are some issues:
1) Dividing Thessaly this way is a bit absurd: there is no precedent of separating western Thessaly from eastern Thessaly iirc. Also, attaching the western half to Epirus is also a bit weird, as the mountain of Pindus would make it a bit difficult for the emperor's reresentative to rule this duchy effectively:
- If he resides in an Epirot city (Arta, if it has managed to recover somewhat from the sacking or Ioannina - although I don't think that they had become a rival centre of Epirus yet), then it is rather difficult to effectively govern those areas of Thessaly. I could see those areas coming under the effective control of local aristocrats, Greek and Latin alike and the Vlachs becoming de-facto autonomous (they supported the Despotate of Epirus when it moved to remove the Crusaders from Thessaly in the 1200s and 1210s and they weren't that supportive of Latin rule), especially if the emperor decides to turn his attention to Asia Minor. IOTL, the Despotate of Epirus only managed to effectively control Thessaly when it was under the rule of capable rulers and from the late 13th century onwards, Thessaly began drifting away from the Despotate and gradually falling under the control of local landowners and aristocrats.
- If he resides in Thessaly (Trikke for example, although I am not sure about its status in the early and mid 13th century), then it would be very difficult for him to exert control over the rugged, mountainous territory of Epirus and starting to fall under the control of local power players, especially its northernmost bits.
2) The same goes for Pelagonia and western Macedonia, although there may not be as many problems here.
My idea: the emperor could attach Pelagonia and western Macedonia, alongside most of the Axios (Vardar) valley to the kingdom of Salonica (as a county or march of Vodena and a county or march of Skopje respectively) and in return, receive some of the easternmost territories of the kingdom (perhaps the territories east of the river Nestus). This would give the empire control over most of Thrace and the crown of Salonica would be compensated. Thessaly remains undivided and under Salonica's rule, but in return, the emperor receives the overlordship of the Duchy of Athens (iirc, Guy de la Roche sided with the emperor when Boniface died, so we could perhaps say that the duchy was in a legal limbo and Robert could perhaps convince the court at Salonica to relinquish its rights over it in exchange for Thessaly and perhaps some bits on the border between Macedonia and Epirus - and the nobles in Salonica wouldn't be able to do much to press such claims).
So we get: Skopje and the Axios Valley , Pelagonia and most of western Macedonia as well as Thessaly go to the kingdom of Salonica, Epirus, the rights over the duchy of Athens (and perhaps Euboea) and most of Thrace go to the Empire. Or the same, but with Thessaly becoming an imperial fief in exchange for the northern parts of Macedonia.
(a rough map of what I am saying; I have also included what the Venetians could pick up).
And feel free to comment!