I think it would be beneficial to the heat sterilized biochar to place it in the fermenter to add good microbes.
Fresh Biochar does in fact have some syn-oil and such between it's pores and so cultivating a strain of microbes that can quickly degrade it, will help with the negative impact that is something seen during the 1st year that biochar is added to soil, when it leaches out 'organic liquids' and by activating the biochar before you add it to the soil you also don't get the usually pull down of mineral from the soil into the biochar pore due to an explosion of soil life between it's pore and it's cation-anion charge.
And some of the dissolved mineral in the compost tea will also will be held and slowly released by the biochar, the same goes for the minerals that get released when the microbes dies/poop/pee/etc.
I have seen some studies that show that the calcium mostly stays put in the bonechar similar to the
carbon in regular biochar. But the phosphorus in the bone char is know to migrate out of the structure about 30% per growing season depending on the temperate at which the bonechar was made.
https://link.springer.com/article/10.1007/s10705-008-9235-6
Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat