docs: state what three cores do without data trees

The Dolphin Sys, PPSSPP assets and blueMSX trees stay required, and the
profiles now cite why. blueMSX finds no machine without Machines/, the
C-BIOS ones included, and the load fails (Src/Board/Machine.c:637-656,
libretro.c:1447-1449). Its tree reference cited libretro.c:1119-1120,
which at the pinned revision is the Sunrise IDE option, and now cites
1196-1197. PPSSPP has no internal font without flash0/font, so
sceFontOpen fails for games using the system fonts
(Core/HLE/sceFont.cpp:805-864, 984-986). Dolphin loads no GameCube font
without Sys/GC/ or an IPL dump and warns that games may crash
(Source/Core/Core/HW/EXI/EXI_DeviceIPL.cpp:328-340).

emulators/bluemsx.yml

@@ -55,6 +55,10 @@ notes: |
   C-BIOS machines work for cartridge-based games without any copyrighted BIOS.
   For disk/tape support, real BIOS ROMs are required.
 
+  The C-BIOS machines are Machines/ entries too. Without the tree
+  machineCreate finds neither config.ini nor a zip for any machine and the
+  game load fails (Src/Board/Machine.c:637-656, libretro.c:1447-1449).
+
   The libretro core zip holds the library only, and the Machines/ and Databases/
   trees come from the buildbot's blueMSX.zip system files. The standalone
   blueMSXv282full.zip ships both trees, machine ROMs included, so every file
@@ -63,10 +67,10 @@ notes: |
 data_directories:
   # 302 files: 296 in Machines/ (200 machine configs + ROMs) + 6 in Databases/
   # buildbot source: https://buildbot.libretro.com/assets/system/blueMSX.zip
-  # ref: libretro.c:1118-1119: system_dir/Machines/ + system_dir/Databases/
+  # ref: libretro.c:1196-1197: system_dir/Machines/ + system_dir/Databases/
   - ref: bluemsx
     installed_on: [batocera, recalbox, retrobat, retrodeck]
-    source_ref: "libretro.c:1119-1120"
+    source_ref: "libretro.c:1196-1197, 1447-1449, Src/Board/Machine.c:637-656"
 
 files:
   # ============================================================

emulators/dolphin.yml

@@ -386,6 +386,16 @@ notes:
     Fonts can come from three sources: real IPL dump (preferred), standalone font files
     in Sys/GC/, or bundled free alternatives. The free fonts have different padding that
     causes text positioning issues in some games.
+  sys_note: >
+    Without Sys/ the libretro core logs that codehandler.bin is missing and
+    goes on. With no IPL dump the GameCube fonts are read from Sys/GC/, so
+    none is loaded, and a game reading them raises "Games may not show fonts correctly, or
+    crash". The per-game settings in Sys/GameSettings/ and the WiiConnect24
+    files some Wii games expect are skipped too.
+    ref: Source/Core/DolphinLibretro/Boot.cpp:313-340,
+    Source/Core/Core/HW/EXI/EXI_DeviceIPL.cpp:128-130, 160-167, 328-340,
+    Source/Core/Core/ConfigManager.cpp:570, 586,
+    Source/Core/Core/WiiRoot.cpp:325-330
   nand_note: >
     Wii NAND content (channels, saves, system menu) is managed by Dolphin internally.
     Users can import a BootMii NAND backup (nand.bin + optional keys.bin) to populate it.

emulators/ppsspp.yml

@@ -19,7 +19,7 @@ data_directories:
     installed_on: [batocera, emudeck, lakka, recalbox, retrobat, retrodeck, retropie]
     mode: libretro
     destination: ""
-    source_ref: "libretro/libretro.cpp:537, 549"
+    source_ref: "libretro/libretro.cpp:537, 546, 549"
 
 notes: |
   Full HLE emulator. No Sony firmware or BIOS required.
@@ -28,6 +28,12 @@ notes: |
   Assets include replacement PGF fonts (18 files in flash0/font/),
   game compatibility database (compat.ini), language mapping (langregion.ini),
   and post-processing shaders (shaders/).
+  flash0/ is read from system/PPSSPP/flash0/ (libretro/libretro.cpp:546).
+  Without its fonts the font library holds no internal font and
+  sceFontOpen returns ERROR_FONT_INVALID_PARAMETER to the game
+  (Core/HLE/sceFont.cpp:805-864, 984-986), so text a game draws with the
+  PSP system fonts is lost. Without ppge_atlas.zim the system dialogs are
+  not drawn (Core/Util/PPGeDraw.cpp:227-230).
   Libretro fork (2020-03-18) behind upstream.
   PSP_DEFAULT_FIRMWARE = 660 (Core/ConfigValues.h:40).