While it was indeed far from their base in Iberia, Aragonese rulers at the time were also rulers of the southern part of Italy, including Sicily. From there it is but a short hop to Albania. (which, like much of the adriatic coast, was dotted with italian merchant communities and occasional holdings of italian states, eg. Venice) this worked both ways (Skanderbeg was important in quelling an italian revolt) to secure Italy and to help stymy various powers in the balkans (like the Ottomans) who would be a potential threat.