I got the game straight from the developer, through the /r/ultrawidemasterrace curator, but like most Unreal Engine 4 games, it simply reduced the field of view the wider it got and it displayed black bars at the cutscenes.
On February 20, responding to a related request, a developer said that the game would receive an update "soon", so I gave them some time and now over a month later the community kept asking for a fix, so I produced one based on my past research and killer-m's approach to implementing FOV calculation.
Going by the developer's response and this release being likely to push them to speed it up, I think it is likely that an update will make the tool obsolete but it's still better than nothing for right now.