What's involved here is a tension between transitive and intransitive uses of the past participle spoken.
Ordinarily a past participle employed as an adjective has a passive sense: the noun modified is the object of the verb, subject of the passive construction:
John did not speak Mary's name, but everyone knew who he was talking about.
Mary's name was not spoken.
Mary's name was unspoken.
Only the past participles of transitive verbs can be employed this way, because only transitive verbs have objects and only transitive verbs can be passivized.
Consequently, the past participles of intransitive verbs are rarely used as adjectives; but there's a handful which are, and in these cases the participle has an active and usually perfective sense.
A widely travelled woman is not a woman who "has been travelled" widely, because travel is used transitively only of places, not of persons; she is a woman who has travelled widely.
A risen dough is not a dough which "has been risen", because rise is intransitive (the transitive version is raise); it is a dough which ****has risen***.
Speak has both transitive and intransitive uses: one may speak a speech or a word AND one may simply "speak", loudly or softly or out or of a topic. And the compounds you adduce employ the participle in different senses:
- Unspoken is a passive use—the entity modified is not spoken.
- There's a verb misspeak which is almost always used intransitively—"When I said that I misspoke"—so in theory the participle would be employed as an active; but I've never actually seen misspoken employed as an adjectival in any sense, and I would be considerably more surprised to find it used actively than passively.
- Outspoken derives from speak out; this is usually intransitive, and in fact the adjective means "given to speaking out", often with the implication that what is said is injudicious or ill-considered.
- Soft-spoken derives from speak soft(ly), intransitive, and means "given to speaking softly" rather than loudly or harshly.