Double _freq_ elements in output file names

I just saw that the index files produced for the new reference dataset (now named as SMHIGridClim) has double _freq_ elements:

tmx_NORDIC-3_SMHI-UERRA-Harmonie_RegRean_v1_Gridpp_v0.9_day_yr_19610101-20181231.nc

Would be useful to replace the _day_ element with _{{frequency}}_ without having to manually specify an output template.