"What if Indomitable Creativity had the creatures enter from the library?"Complex replacement effect interactions were never my specialty even before the hypothetical... But my initial concern is based on anything that messes with the library as part of a replacement effect.

Firstly, while I can't think of replacements that require payment off the top of my head, Chromatic Sphere's card draw mana ability always makes me wary.

The potentially messier example would be Devour ('as ~ enters you may sacrifice creatures') combined with Blightsteel Colossus ('if it would die, shuffle it into your library instead), for which I'd love confirmation/correction from less rusty rules experts.

While applying replacement effects you haven't yet made zone changes, but this would end up with the game attempting to move cards from the library at the same time as they were being shuffled away. (And I've no idea what the current precedent is for that, if one exists.)

Even in the event the rules can handle the above scenario, it would be intentionally allowing a messy interaction for questionable gain. There would always be a group that insisted the ruling was incorrect. ("Never give an order you aren't certain will be followed.")

An FYI with someone more familiar with the rules.

Is Indomitable Creativity a color pie break?

No, it is us trying something new in Red.