18. The supervisor is especially fond of arranging training programs, working on elaborate projects, and to develop projects.
You are correct! The sentence is grammatically wrong.
The error is in "...to develop budgets." It should be in the same form as the other two in the list, "arranging training programs" and "working on elaborate projects." The components of a list should all be the same part of speech.
You are correct! The sentence is grammatically wrong.