Her accent is pretty thick, but I would call her fluent.
There isn't like... a huge leap between her and Fuwamoco. It's still a jump, but not too distant.
I also think Ririka's English has improved/revitalised over the past year as she's had more reason to speak it on a (semi-)regular basis.
I remember being impressed at her debut as well, but she sounds even smoother now I think.
It's fun watching clips where she basically becomes interpreter for other JP girls.