https://forum.renoise.com/t/convolver-applies-dc-offset-filtering-to-impulse/44886
Here is a thread with discussion regarding certain characteristics of the convolver. Seems like you’ve discovered another quirk loading the exact impulse into the convolver as IR 
nice idea to come up with… To me it looks like some minimum phase filtering happening, maybe DC filter, and resampling filter also, then the convolver has this crappy tone control that maybe also has its impact in center position. You know…the 1 sample spike is kind of a very perfect theoretical impulse, containing components that aren’t audible, DC and very high freq components - if that stuff was removed with filters, and also phases of frequency components moved by these filters, the result can look like what we get here. It should sound right about the same though, unless you modify it in certain ways. Maybe it is one thing to watch for when convolving IRs multiple times with each other, to use a convolver with direct throughput for the task, to evade possible degradations of the data?
As for the pre-ringing, I have not thought much about that yet, I mostly use the convolver for reverbs and delay like effects, maybe sometimes to simulate resonance of a body with my sounds inside it, so organic sounds rather… I’m rather excited by these techniques as they allow to craft such impulses, and tune them to the liking, I have not much tried to conserve certain plugins trying to be exact. Maybe the “best” way to handle pre ringing DSP would be to know the exact PDC of a plugin (there’s plugins that can measure I think) and add just as much silence, and adding the right artificial PDC (yep there’s also plugins that can do this) to a track doing only the convolver wet. To cut the ringing would always mean changing the sound, even if you use the standard optimal windowing functions to try to lessen the effect…as you cannot really window the tail of the starting impulse for more complex effects at the same time, it would change the sound even more than normal “windowing” operations that usually operate on both sides in symmetry. There are also mathematical ways of creating “minimum phase” versions of FIR filter kernels (an IR is just that), by shifting phase and eleminating any preringing, fucking up the IR even more while doing this…but I think those only would make sense on very simple filter kernel.
I don’t know if there’s actually many plugins, that add PDC and at the same time use the headroom for linear FIR filter pre-ringing. Maybe those linear phase mastering EQs do that by default, there it is to be expected. Then cutting away the ringing should have rather drastic effects on the tonal ballance.