It is not a bug, it is a technical limitation of the underlying technologies that Kurviger uses. It is not related to your phone’s memory nor it’s processing power, but to the amount of data the external software components can accept as input.
@boldtrn already commented on this in another thread:
So, there is apparently no quick fix for this limitation, as Kurviger probably does not have the leverage to enforce the change of the external software components.
The workaround is to split the route in 2-3 sections.
One thing that should not happen is - the app should not crash. It should report the limitation and offer a solution to the user (split or shorten the route).