What is the purpose of the --localize flag when packaging a solution?

[szmarci]

According to the docs when using the --localize flag with pac solution unpack, it supposed to do this:

Extract or merge all string resources into .resx files.

Which it does. It creates a Resources folder with a bunch of .resx files.

My understanding is that at this point I am free to modify these generated files, changing the translations, etc... And when I repackage the solution with this command pac solution pack --localize it reads these files during the process and puts them into the final .xml.

The problem is that this is not happening. I get these logs during packaging:

Found 47 localization resource(s) files
Localizing Component: SolutionManifest
Localizing Component: Entities
Localizing Component: Roles
Localizing Component: Workflows
Localizing Component: FieldSecurityProfiles
Localizing Component: Templates
Localizing Component: EntityMaps
Localizing Component: EntityRelationships
Localizing Component: optionsets
Localizing Component: MobileOfflineProfiles
Localizing Component: Dashboards
Localizing Component: InteractionCentricDashboards
Localizing Component: WebResources
Localizing Component: CustomControls
Localizing Component: AppModuleSiteMaps
Localizing Component: AppModules
Localizing Component: EntityDataProviders
Localizing Component: CanvasApps
Localizing 356 solution component files(s)...

But at the end of the process when I unzip the solution and try to look for my custom strings in customizations.xml I added before the packaging, they are nowhere to be found.

Is something I am misunderstanding about the purpose of this command?
Or is this a bug?

[MassoudDehkordi]

The issue @szmarci reported more than a year ago, is still present.
pac still cannot be used to replace SolutionPackager (something that we want to do) as L10N .resx files are not packed back into the XMLs.