I'm sure you're also able to indicate the roles of tenant and landlord in Spanish. But just like in English, you're not required to.

Right! You have "propietario" (the person who owns the property) and "inquilino" (the person paying the rent). But confusingly enough the verb is still "alquilar" ("to rent") for both :)

So if you say "voy a alquilar esta casa" ("I'm going to rent this house") it's not clear whether you're the landlord or the tenant.

"Renter" would also be ambiguous, although "lessor" and "lessee" do have specific meanings.

In Swedish, it's also the same word ("hyra") but the meaning is conveyed by adding "ut" ("out"). So the tenant hyr what the landlord hyr ut.