From listening Albert Pyun's audio commentary of his CYBORG director's cut, MASTERS 2 and SPIDER-MAN were in prep in December 1987 (soon after the Black Monday which put Cannon into trouble), so while MASTERS 1 was still barely opening in Europe, therefore they launched the sequel while they didn't have the total gross yet.
What a lot of people also forget to mention is that after SPIDER-MAN and MASTERS 2 fell through, Pyun wrote the script of CYBORG from two other previous projects he had: his own remake of JOHNNY GUITAR designed with John Travolta in mind, and ALEX RAIN which was like an early version, precursor to NEMESIS with Kelly Lynch cast as the lead (she had just done the post-nuke flick OSA).
And the funny thing about SPIDER-MAN is that Joseph Zito had dropped the project he had worked on for quite a while (until Cannon shrunk the budget again) to do RED SCORPION, which was in production when Pyun got on to it and MASTERS 2...