Comment (by Yosef Zlochower):

Yes, please add it the the master thornlist. I think the only outstanding issues is that there needs to be documentation added and a testcase constructed that shows the output values are as expected. For the latter, I was thinking of proposing filling fields with low-order polynomials and then determining if the interpolated values match the polynomials to roundoff precision

--
Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2416/add-readinterpolate-thorn-to-einstein