While 'equifinality' seems to be the term you were looking for, I thought I'd mention an adjective that's sometimes used to express the same idea: convergent.
- tending to move toward one point or to approach each other (convergent lines)
- exhibiting convergence in form, function, or development (convergent evolution)
- of an improper integral : having a value that is a real number
- characterized by having the nth term or the sum of the first n terms approach a finite limit
The usage in convergent lines (first meaning) clearly matches the idea that multiple lines (paths, if you will) can reach a common point, without implying that all lines will.
The second meaning is better exemplified in Wikipedia's description:
Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. ... The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions.
Different metaphorical paths can lead to the same outcome, e.g. flight. Interestingly, in this usage the eventually reached states don't have to be the exact same ones - only that they need to show analogous features or effects.
The third meaning is from mathematics, where it's not always clear that different paths exist. In most math-related cases it's probably better to think of convergent as a technical term. However, a clear example of multiple paths leading to the same number can be found in the convergence of random numbers. Most straightforwardly, if you repeatedly roll a fair die and calculate the average of all rolls, this will eventually converge to 3.5, no matter the order of the rolls.
For more examples see Wikipedia's disambiguation page for convergence. Do note that not all those terms necessarily mean that a common goal is reached, however.