Basically my win conds are all focused on the 3 eldrazis and I have almost no way to interact outside Gone Missing and Compelling Deterrence. Should I move into white/green for the fliers, the Puncturing Lights and keep the blue eldrazis onboard?
I'm not a fan of the switch. Elder-Deep Fiend is one of those cards that will just single handedly win you a game on turn 4, and it's not very splashable as it costs double blue. My take on the pool is that your bombs are good enough that you just need to accept the cost of not having that many ways to interact with your opponent. I would consider splashing if your white had Choking Restraints or something along those lines, but Puncturing Light isn't good enough to hit many of the bombs / finishers in the set, so I don't think it's worth it.
As for the build itself, I think I would go:
+1 Ghostly Wings
Your deck doesn't need 7 1-2 drop creatures, and Ghostly Wings can interact with your opponent or force through a dumb ground idiot for damage. While I don't normally like the card, I think it does enough for your deck that it's worth playing.
I'd definitely stick with UG, none of the other colors are impressive or bring anything nearly as impressive as Fiend/Decimator to the table. Is your deck imperfect? Absolutely, the lack of removal is an issue. But at least the UG build has a couple of bombs in those two that can just win games out of nowhere.
Switch to something like UW or GW and maybe your deck is more well-rounded, but it is also extremely mediocre and still likely to lose to opposing bombs while giving up win% in the form of not having something like the Fiend to lean on. It isn't always correct to play your bombs like that, sometimes the colors they are in are just too shallow, or you just have awesome synergy/quality elsewhere (I had this happen in my last pool, where I had Fiend, Drogskol Calvary, and Spell Queller as my most exciting cards, but terrible shallow UW with like 12 cards I wanted to play between the two colors. OTOH my black and red were very deep with quality creatures and removal, and had a high number of madness enablers and madness cards to add some synergy to the deck. No bombs but I still went 4-1 on the back of a solid curve and a boatload of removal). But in this case both blue and green lead your pool in quality AND boast your bombs, so you'd need a huge reason to not play them.