Even with many things indicating it, no. Yae is not the previous Electro Archon.

Who is the Archon of electro?

Beelzebul, the name of the current Electro Archon, is associated with this demon. For an unexplained reason, Paimon is also named after one of the 72 demons, specifically Paimon, one of the kings of hell.

Who is the original Archon?

Liyue's Morax, the God of Contracts, is the oldest Archon in Genshin Impact, with at least over 2000 years under his rule. Naturally, as a god centered around order, Morax has a very different relationship with his people.