You can’t just back-transform the same way that you do with the beta estimates you get from the survival analysis, e.g.
To get the SE value for a particular beta value you need two values, the beta estimate and the SE of the beta estimate.
So, if your estimate of beta = 0.2648 and your estimate of SE for beta = 0.14467 then,
So, if your estimate of beta = 0.2648 and your estimate of SE for beta = 0.14467 then,