As of Dynare 5, when you use steady_state(T) where T trends with
trend_var(growth_factor=gz) z;
var(deflator=z) T
it will use the steady state of the detrended T. Denote with a tilde the detrended stationary objects and with a bar the steady state. steady_state(T) will use \bar {\tilde{T}}= steady\_state\left(\frac{T_t}{z_t}\right). In contrast, if you use steady_state(T(-1)) it will use \bar{\tilde{T_{-1}}}=steady\_state\left(\frac{T_{t-1}}{z_t}\right)=steady\_state\left(\frac{\tilde{T_{t-1}}}{gz_t}\right)=\frac{\tilde T}{gz}.
Put differently, an equation will always be divided by the respective time t trends and the required growth factors for variables containing other trend timings are preserved when applying the steady_state()-operator to variables with a different timing.
Note that you can inspect the transformed model using write_latex_dynamic_model.