From the PS2 game, we can safely assume that…

Yes, Hibari and Tsuna can talk normally. Contrary to popular beliefs that Hibari always talk with his tonfa.

As seen in the ps2 game, Hibari is able to hold a normal-without-biting conversation, and Tsuna can talk with Hibari….as long as some requirements present. For example, the fact that Tsuna is not crowding…and not getting panic first. (They’re just like animals lol if you don’t show hostility first, he won’t bite. If he saw you proceeded calmly, he won’t get panic. Animals boyfriends XDD)

This condition has also been already seen in the manga where Tsuna could talk to adult Hibari without wanting to run away first and Hibari talked casually in the snowball fight chapter.

As seen in the ps2 game, Hibari returned Tsuna’s greeting casually and answered all his questions. The scene shifted showing the two were walking together. At one point, Tsuna proposed the idea of jankenpon out of nowhere and without asking, Hibari went along. Hibari asked for a gift for being a winner but I-pin came so he left the scene afterwards without any biting happened and no longer demanded it afterwards. They can interact normally. Tsuna just needs to get used to Hibari’s quirks.

In the other ps2 game, in Tsuna’s story mode, Tsuna’s seen to be in a room with Reborn and TYL!Hibari together, for most of the start of the chapters. Nope, no biting and no screaming happened in there until the point of the chapter came.