Tense marker used to express events/conditions/etc. that are actually happening.
Tense marker for actuality.
Meaning of {ca'a} used as sumtcita is unclear.
Tense marker used to express innate capability for events/conditions/etc. to happen — regardless of those events/conditions/etc. actually taking place
Tense marker for innate capability.
Unlike {kakne}, {ka'e} expresses innate, potential capability, which doesn't have to be an actual, present capability. The difference is best illustrated by an example: birds (except for few species) can fly (lo cipni cu ka'e vofli) but among them there are some that cannot do so now (ti poi cipni na kakne lo zu'o vofli) due to being crippled, too young, confined in small cage, etc.
{ka'e} covers all situations where {pu'i} and {nu'o} are applicable (is more general than both of them).
Tense marker used to express capability which was demonstrated at least once.
Tense marker for demonstrated capability.
Unlike {ka'e}, {pu'i} requires a capability to be demonstrated (that is, actually used) at least once. If that's not the case (but {ka'e} still applies), use {nu'o}.
Tense marker used to express undemonstrated capability or unrealised potential.
Tense marker for undemonstrated capability.
{nu'o} requires a capability to not be demonstrated/used/etc. even once. It is applicable in situations where {ka'e} is but {pu'i} is not.
Not to be confused with {na'o}.
There is also apparently little-to-no difference between {nu'o} and {na'epu'i}. Further investigation needed.