Sorry, It seems that not the case...
New fresh install (locally so far) with system default en-US
enable fr-FR, es-ES, de-DE, it-IT
set site-default fo fr-FR (my browser is in en-GB, my college's in es-ES)
deactivate "language parameter in url"
enable "browser language detection" and "users choose interface language"
eliminate all languaje alias, left only root with no languaje specific
create a user (not admin) and set preferred locale in de-DE
create and install own module that shows just a hello in the corresponding language (with resource files for all languages)
create three pages: a, aa, aaa (with one instance of the module, two instances, and three instances)
SET "a" as home
then, new browser session, go to localhost:2037 -> it shows the site in fr-FR WRONG
type /a -> and display localhost:2037/languages/en-GB/e (from my browser default) WRONG (becouse the language in the url)
logon and go home, display fr-FR WRONG
go any other page, display in de-DE (my preferred locale) right !!
SET <None Specified> as home
then, new browser session (no cookies, no cache) -> and home shows "a" with my browser default PERFECT ! (but surprise why it still gets "a" as home)
logon, go any page, it shows in de-DE, go home, shows "a" in de-DE , again PERFECT !
go to site settings -> behaviour-> default pages, and in the home page tab, "a" is still selected WEIRD !! but works
SET anypage as home, save, set "a" as home, save
again back to the wrong behavior
as any page is set as home, several (two at least) "things" get updated, something in the url parsec/resolver, and something in the page configuration "thing"
as <none specified> is set, one of them (url parsec/resolver) is set to none and that correct the problem, while the other/s (page configuration) still points to "a"
the problem with this, is that the behavior is erratic (we have find some other effects on subpages when the home problem seemed solve)
I do not know what is the perspective of DNN team towards the languages, but something more simpler should be done than whatever is implemented today that keep crashing, I would suggest to remove completely the language from the url and move it to a ?loc= attribute, and define a simple rule to show a portal in a language: first ?loc attribute, second user-prefer-locale, third browser-detection, fourth site-default, fifth system-default. And that's all !!
We are happy to help the community, as done in other cases,
I could create a public DNN site with reproductability of the error if you wish