Aldostools said in webMAN MOD's GitHub repository that using SEN Enabler isn't safe anymore because many validations have changed on PSN servers side so I guess I shouldn't use it to spoof the PS3 and I should delete it and wait for a CFW that supports the latest FW is out.
EDIT: It seems it's possible to access the PSN safely without using SEN Enabler to spoof the PS3 if using webMAN MOD, uploading a file called "ps3-updatelist.txt" to "/dev_hdd0/ps3-updatelist.txt" and restarting the PS3 or of if using webMAN MOD and installing webMAN - System Spoofer on the PS3 (which actually extracts the "ps3-updatelist.txt" to "/dev_hdd0/ps3-updatelist.txt"). The "ps3_updatelist.txt" file must match the latest FW or it won't work. Since I don't want to install webMAN MOD, I'll wait until a new CFW that supports the latest FW is out.
EDIT 2: Apparently, all PS1 emulators have harcoded PS1 game configurations, ps2_emu, ps2_gxemu and ps2_softemu have hardcoded PS2 game configurations and only ps2_netemu can load PS2 game configurations from an external file.
EDIT 3: It seems it's also possible to access the PSN if installing Evilnat [D-PEX] or Evilnat [PEX] (I did the latter because Rebug is obsolete) and after following
these steps to convert to DEX.
EDIT 4: I think the PS3's external HDD where the PS1 and PS3 games are stored is no longer vibrating but it's always very hot (like the PS3, which is noisy). Maybe I should place it on top of another thing since I don't know how to unscrew the PS3 to clean it and apply new thermal paste.
EDIT 5: Now, after deleting RetroArch, downloading it (from Brewology, since the last time it was available in RetroArch's official website was in 2020 [it was the 1.9.0 version and it appeared by the name "PSL1GHT", as well as some previous versions]. Since then, RetroArch's official website says "Coming soon" in the PS3 section), reinstalling it, running it, loading a ROM, loading a core, changing its "Aspect Ratio" setting and loading another ROM with a different core, it kept the previous "Aspect Ratio" setting so I didn't have a white screen but when loading ROMs with the Gearboy core, the console returns to XMB, and when loading Pokémon Emerald, it doesn't let me choose the core and automatically chooses the VBA Next one.
EDIT 6: I tried RetroArch CE (unofficial beta updated 2022-03-15), and after loading ROMs with the Gearboy core a few times, the console didn't return to XMB, and when loading Pokémon Emerald, it let me choose the core I want to load.
EDIT 7: RetroArch's official website says RetroArch is "Coming soon" in the PS3 section (it does it for years) and that in the meantime unofficial versions of it are available elsewhere.
EDIT 8: I gave webMAN MOD a new chance and before reinstalling it I deleted IRISMAN. The "webMAN games" setting was empty with my external HDD connected to the PS3, which is odd. I disconnected it, restarted the PS3 and it wasn't empty. I installed prepISO and use it to scan the external HDD connected to my PS3 every time I make changes to my PS1 and PS3 games (which are now in the same partition) since the external HDD is formatted as NTFS. I wasn't being able to connect the PC to the PS3 via FTP using FileZilla Client and webMAN MOD until I did
this. Also, webMAN MOD already comes with PS2 CONFIG Database installed which contains CONFIG files (like I was told).