If we follow Terrydm's excellent answers for the translation of "friends forever" we get Amici aeterni pronounced: uh·mee·chee ay·tur·nee or amici in aeternum pronounced: uh·mee·chee en ay·tur·num. For two females amicae aeternae pronounced: uh·mee·chay ay·tur·nay or amicae in aeternum pronounced: uh·mee·chay en ay·tur·num. I provided these phonetically instead of with accepted pronunciation characters because it's easier to understand. I hope.
Friends forever
karɪdʲan gə braːx
Semper amici.
The Latin word for 'forever' is aeternum.
"Forever sisters!" in English is Aeternum soror! in Latin.
Amici aeterniAlternative:Amici aeterni is "eternal friends"; I interpret "forever" in this phrase as an adverb, not an adjective, and would go with a translation of amici in aeternum. (Note that if both of the friends referred to are female, it would be amicae aeternaeor amicae in aeternum.)
Best Friends Forever
You can say friends forever in Italian by saying amici per sempre. Friends forever in Russian is druz'ya navsegda. Friends forever in Spanish is amigos para siempre.
In French, "forever" is pronounced as "pour toujours."
Sometimes it can be hard to translate English sayings to Latin. The Latin translation for "Scotland Forever" is Semper Scotia.
In English pronounce it .....Cumri am bith....Wales forever
In perpetuum.