ZDoom

ohhhhhhh alright then, I suppose in that case it IS consistent with at least one of the results I found for this. thank you, that seems to work so far! But why does gzdoom care enough to complain but not to make stuff not show up? in fact at first I tried to use a folder called "spreefs" but I couldn't get slade to acknowledge it. Putting sounds into a folder called "noise" works without issue, fortunately.
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AH I assume the game was actually reading that stuff twice. Once because I told it to, successfully, and a second time automatically just because stuff was in the sprites subfolder, and that was NOT successful, hence the cavalcade of errors, and it just only reported once stuff that appeared to have the same 8 character extensionless name.

You are not supposed to place non-sprite data into the sprites folder. Everything in there has to strictly follow the original naming conventions, i.e. SSSSF# or SSSSF#F# where SSSS is the internal sprite name, F is the frame letter and # the rotation index. This all needs to go into patches, not sprites.

[attachment=0]errorheap.png[/attachment]
and on like that. The game runs as well as ever, but these complaints are rather conspicuous as the whole thing is starting up.
I did a search for R_installspritelump on the forum and it seems generally to not show up in this context. I run these from a batch file with several other wads whose contents I had been gradually migrating into a single folder, but for the moment omitting any of those creates additional errors that prevent the game from starting.
I am using gzdoom version 4.10, but up until a moment ago I think i was using 4.7. In windows 7. This started as soon as I began using a folder formation for texture definitions and the number of these errors has steadily increased as I added more. Today a whole bunch more appeared and the list is now quite absurd in length I assume this is a bug because the system does not report EVERY sprite I have defined like this, and none of them fail to show up. It also does not report the full names of the graphics it is getting confused by if they have more than 8 characters.
[c]Sprite "FOPPA4", 740, 1060
{
Offset 370, 1020
Patch "SPRITES/FYIP/FYOPPAIN4-1.PNG", 0, 0
Patch "SPRITES/FYIP/FYOPPAINHAT4-1.PNG", 0, 0
Patch "SPRITES/FYIP/PAINBELLS4-1.PNG", 0, 0
}
[/c]
like so

[c]Sprite "YWAHH8H2", 550, 993
{
Offset 275, 950
Patch "SPRITES/YETH/YWAH8-8", 0, 0
}[/c]
and it seems to be unrelated to if they have extensions. I thought my switching to dashes from the letter a (for "angle" (to confuse myself less)) around the same time I started using folders might have started it, but switching the dash back to A did not get this one off the list and it seems illogical to try every one of them.
I would hate to go back to folderless mode just to stop the errors; my wads have been chronically messy and confounding for [ever]. In fact I wouldn't even know how to back-convert it at this point and would probably live with the errors first if it were necessary to choose.