Solarpunk technology

Dolphins, whales, apes, bats, elephants and prairie dogs would be good candidates. For most species however, since their repertoire of communication is quite limited, attempting communication wouldn't be likely to succeed.

https://en.wikipedia.org/wiki/Animal_language

Prairie dogs, being a species well accessible by humans (they live in fixed underground "settlements", don't swim or fly where people cannot record them, and aren't dangerous to approach) have been studied to an extent, and their language does have semantics:

Their calls transmit semantic information, which was demonstrated when playbacks of alarm calls in the absence of predators led to escape behavior appropriate for the types of predators associated with the calls. The alarm calls also contain descriptive information about the general size, color, and speed of the predator.[25]

I imagine that prairie dogs are already capable of coming up with statements like "big cat coming slowly from north", so maybe some of their colonies, in the right conditions, develop more complex language. Since they don't travel much, each of their colonies might have a different language, however.

Perhaps the most interesting language would be that of squids:

In addition to camouflage and appearing larger in the face of a threat, squid use color, patterns, and flashing to communicate with one another in various courtship rituals. Caribbean reef squid can send one message via color patterns to a squid on their right, while they send another message to a squid on their left.[38][39]