Hi,
as a matter of fact I ran the engines before searching for presets, having already the required Osirus/Ostirus ROMs installed in the appropriate places, but it didn’t make any difference.
Of course, I performed the search for presets routine both before and after having instantiated a plugin.
Anyway, I reinstalled the ROMs via the appropriate DSP56300 upload tab on webconf, not manually or using the file browser.
I am aware enough, at this point, of the way the TUS emus work on the Z, since it is one of my fave topics, but re-checking the relevant past threads does certainly no harm! 
I will check in:
and possibly erase everything contained, before associating anew a plugin to a chain, thus trying to (auto)-generate presets again.
BTW, is this command still functioning?
regenerate_lv2_presets.sh http://theusualsuspects.lv2.Osirus
Best 