“Goes” and “may” are both present participle, whereas “went” is simple past participle. To match “went”, one would have to use the word “might” (simple past participle of “may”). The choice of the word “might”, however, is inappropriate in this context because it is referring to something that would happen in the future (and is less than certain to), and the word “might” typically refers to things that could have happened in the past. “May” refers to things that are likely to happen in the present or future, making it the appropriate word choice.
Also, there is no imperfect tense in English. That would be the continuous tense.