I re-installed Linux and it gave me those message, are they worth something?

(1/1) reinstalling linux

Updating module dependencies. Please wait ...

:: Running post-transaction hooks...

Updating linux initcpios
==> Building image from preset: /etc/mkinitcpio.d/linux.preset: 'default'
-> -k /boot/vmlinuz-linux -c /etc/mkinitcpio.conf -g /boot/initramfs-linux.img
==> Starting build: 5.1.15-1
==> Generating module dependencies
==> Creating gzip-compressed initcpio image: /boot/initramfs-linux.img
==> Image generation successful
==> Building image from preset: /etc/mkinitcpio.d/linux.preset: 'fallback'
-> -k /boot/vmlinuz-linux -c /etc/mkinitcpio.conf -g /boot/initramfs-linux-fallback.img -S autodetect
==> WARNING: Possibly missing firmware for module: aic94xx
==> WARNING: Possibly missing firmware for module: wd719x
==> Creating gzip-compressed initcpio image: /boot/initramfs-linux-fallback.img

Comando terminato OK!

I think I didn't post this one before, I apologize for that

pacman -Qi linux

Nome : linux
Versione : 5.1.15-1
Descrizione : The Linux Kernel and modules
Architettura : x86_64
URL : http://www.kernel.org/
Licenze : GPL2
Gruppi : base
Fornisce : acerhk=0.5.35 aufs3
Dipenda da : coreutils linux-firmware kmod mkinitcpio>=0.7
Dipendenze opzionali : crda: to set the correct wireless channels of your
country [installato]
→ (Required by) Richiesto da : tomoyo-tools
Opzionale per : Nessuno
Conflitti con : acerhk
Sostituisce : aufs3
Spazio richiesto : 128,84 MiB
Pacchettizzatore : Anke Boersma <demm@kaosx.us>
Data di creazione : mar 25 giu 2019, 12:11:36
Data di installazione : gio 4 lug 2019, 18:48:27
Motivo dell'installazione : Installato esplicitamente
Script di install : Sì
Convalidato da : Somma SHA-256

As expected, the kernel did not have the needed module, you must have done this before.....
Please post the output ls /lib/modules
But this is not the proper solution. As you now already noted, you forget about installing packages. Never install any outside of the package manager, you will end up with untracked files you don't remember where they came from, always use PKGBUILD/makepkg to install any.
https://kaosx.us/docs/package/
Example of a PKGBUILD for another RTL wifi module:
https://github.com/KaOSx/main/blob/master/rtl8192eu/PKGBUILD

With kernel modules like these you have to rebuild it on any kernel update, see the history for the above mentioned module

a month later

I apologize for the huge delay in the answer

ls /lib/modules

5.0.9-1/  5.1.14-1-next/  5.1.15-1/  extramodules-5.1/  extramodules-5.1-next/

As you show, you did this before, and now have a bunch of untracked files. The manual installs did not take care of the fact that there are no longer kernels available for 5.0.9 & 5.1.14 next in KaOS.
Make sure to follow the info from my previous post and let pacman/makepkg do the installing & tracking of any you add.

a month later

I have to be honest, I'm not undestanding anything of this or how to create a package or how to track files.
I would have preferred a way to keep this things at a central level, and not at my basic user level