I wrote a sentence on my own jokingly.
How cool would it be, if I could have infiltrated the Kremlin, steal the Tsar's throne and return to my peaceful home unharmed
Regarding that sentence my friend told me, it would have been grammatical if I wrote it in the following way
How cool would it be, if I could have infiltrated the Kremlin, stolen the Tsar's throne and returned to my peaceful home unharmed
The BOLD parts are changed in the last sentence. The reason he told me was that the could have part should be followed by past participle form of every verbs. So as I had written "could have infiltrated", I should have used stolen and returned for the same reason. Is it true?
To me, if I could have infiltrated the Kremlin, I am like gone to the fictional time and now what I was about to do is like happening in the present of that time. So I used present tense.