Triology means a group of three related plays, novels, albums, etc. Or from its Greek origin, it refers to three tragic plays in a row, played one after the other.
A 'triologist' would be someone responsible for the writing, creating, or playing the group of three items.
An alternate word to triologist is Trichologist. A Trichologist is someone who is a specialist in the promotion of healthy hair and scalps.
"Triologist" is not a commonly recognized term. It may have been misspelled or misused. If you provide more context or detail, I can try to give a more accurate answer.