Exclusive we is actually found in many languages, but usually it's the listener who is excluded. Malay kita "we" includes the listener, kami excludes the listener.
Yes we have vosotros (in Spain) or ustedes (in the rest of the Spanish-speaking world -can't speak for Equatorial Guinea though). But we don't call it a 4th person pronoun. It's just the plural form of the 2nd person pronoun:
1st singular: I / yo
1st plural: we / nosotros
2nd singular: you / tú, vos, usted if you wanna be formal
2nd plural: plural you, y'all / ustedes, vosotros
3rd singular: she, he, singular they / ella, él, elle (that last one mostly used among the young queer/progressive community in some countries)
3rd plural: they / ellos, ellas, elles (same above)
Don't know what a 4th person pronoun would be. And I'm a Spanish teacher in South America lol