The Planets around Tau Ceti may be fairly volcanic

[stevebowers]

Yes, but as rocky planets get larger, they also get denser due to compaction at the core. A large, low density rocky planet is unfeasible. Even with no iron core, a rocky planet with 4.3 Earth masses would have a maximum radius of around 10,000km; this gives a surface gravity of around 1.75 gees. If the planet has any core at all it gets smaller and denser quite quickly, and the gravity increases accordingly. 1.75 is about the lowest that Elysia's gravity could reasonably be; not much more than your estimate, but still quite high (and quite unlikely).

I'm getting a radius of 9750 km for an Earth-like composition, and a surface gravity of 1.85 gees.
If Elysia is a waterworld then it could be a lot larger, and have a lower gravity; perhaps this would make it a suitable world for colonisation later in the scenario.