Anything that requires a decides context just means do wrap it in an if statement!
Checking a value in an Array always needs to take place in a decides context, other functions as long as they have the <transact> specifier, can be in there too.
if:
rndmnumber := GetRandomInt(0, Wordlist.Length) #not decides but can be in here
RandomWord := Wordlist[rndmnumber]
then:
Print(RandomWord)
if:
chooseword[]
then: