I didn't inspect Spenser route choices so deep. I am also didn't get the best ending for him in a first try. Maybe someday i will go through his route code, but right now i didn't have certain advice for you except just play the game and engoy your time with him. Or try some other routers and comeback to him with fresh look on every decision. But if you want his best ending so much - visit Dyne's patreon. There are guides for best endings at some level of support.