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it's also possible to access the PSN if installing Evilnat [D-PEX] or Evilnat [PEX] (I did the latter because Rebug is obsolete) and after following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 in another place 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 installed Evilnat 4.93 [PEX] and gave webMAN MOD a new chance and before reinstalling the latter 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 was no longer empty. I installed prepISO, connect the external HDD to the PS3 (the "webMAN games" setting is no longer empty) and use prepISO to scan the external HDD every time I make changes to my PS1 and PS3 games in the external HDD (which are now in the same partition, since when I was using IRISMAN I wanted to be able to toggle between the PS1 emulators and I couldn't do that if running PS1 games from the external HDD's NTFS partition where my PS3 games were but only if running the PS1 games from the external HDD's FAT32 partition [and it had to be the first external HDD partition, because if not, the PS1 games weren't even found]) since the external HDD is formatted as NTFS (also, IIRC, even after using prepISO, it wasn't reflecting the changes I made to the PS1 and PS3 games in the external HDD when it had two partitions [a FAT32 one for PS1 games and a NTFS one for PS3 ones] but it does after putting them in a single NTFS one). Also, webMAN MOD already comes with PS2 CONFIG Database installed which contains CONFIG files (like I was told).