Hi Rubens,
The Team are just finishing up their Summer break and should be back to answer your questions over the next few days. I've just set-up a test Project selecting Desktop / Bootstrap and then added the Electron Platform and all worked including Capacitor being installed and set as the runtime for the Project. My output is below:
Updated Node Package: @capacitor/core ^5.7.8
Installing Node Packages...
added 2 packages, and audited 3 packages in 1s
found 0 vulnerabilities
Copy files for capacitor_core
Node Packages Installed Successfully!
Copy file capacitor.js
Copy file capacitor.js.map
Linux Homebrew is correctly installed.
Checking NodeJS installation and version...
v20.18.1
NodeJS is correctly installed.
Installing Capacitor ...
added 107 packages, and audited 110 packages in 2s
19 packages are looking for funding
run npm fund
for details
found 0 vulnerabilities
Copy files for capacitor_core
Checking NodeJS installation and version...
v20.18.1
NodeJS is correctly installed.
Checking Capacitor installation and version...
7.4.2
Capacitor is correctly installed.
System check successful!
If you are experiencing some build errors please make sure to check the Platform Guide for electron:
Added Node Package: @capacitor-community/electron *
Installing Node Packages...
added 26 packages, and audited 136 packages in 3s
found 0 vulnerabilities
Adding electron to your project ...
Node Packages Installed Successfully!
- Adding Electron platform
- Adding Electron platform: start

Adding Electron platform: start 
- Adding Electron platform: extracting template
Adding Electron platform: extracting template
- Adding Electron platform: copying capacitor config file
Adding Electron platform: copying capacitor config file
- Adding Electron platform: setting up electron project
Adding Electron platform: setting up electron project
- Adding Electron platform: installing npm modules
Adding Electron platform: installing npm modules
Adding Electron platform: completed in 17.92s
- Copying Web App to Electron platform
- Copying Web App to Electron platform: start

Copying Web App to Electron platform: start 
- Copying Web App to Electron platform: Copying /home/anon/Documents/Projects/testElectron/www into /home/anon/Documents/Projects/testElectron/electron/app
Copying Web App to Electron platform: Copying /home/anon/Documents/Projects/testElectron/www into /home/anon/Documents/Projects/testElectron/electron/app
Copying Web App to Electron platform: completed in 2.06ms
- Updating Electron plugins
- Updating Electron plugins: start

Updating Electron plugins: start 
- Updating Electron plugins: searching for plugins
Updating Electron plugins: searching for plugins
- Updating Electron plugins: generating electron-plugins.js
Updating Electron plugins: generating electron-plugins.js
Updating Electron plugins: completed in 1.40ms
electron added successfully!
Copy files for capacitor_core
I can not replicate your issue specifically. All seems to be working fine here on 7.1.2 Ubuntu.