I'm trying it but it seems I didn't get something ...
The training dummy should appear in the workshops lists, right ?
There is the soap maker's one but not this one, for me ...
I made separate files for both the building and the reaction, could it come from here ?
I *think* I've heard having seperate files for them is fine, but it they probably need to start with building and reaction, respectively. Most likely though, the problem is you need to regen the world.
For modding:
If you modify an existing entry (say, change the reagents required for a reaction), you do not need to regen the world, just edit the raws in the save folder.
If you add a new entry (i.e. new buildings or reactions), you must regen the world to see them.
I've restarted a few times due to adding mods; one thing you can do if you like the location of your fortress is to abandon it (make a copy of the save folder first if you want), load it in legends mode, and export the world gen settings used, so that you can recreate the world.
Another thing I've done is to add about 15 buildings and 60 reactions to the custom files, with names but no details. These "dummy entries" should allow me to and in new buildings and reactions later without regening, by editing the entries to add details.