How does Ekko's Chronobreak spell interact with token units?

No — a token you banish with Chronobreak is gone for good; it never gets played back. Chronobreak banishes the units, then has each owner play them back ignoring cost, but a token that leaves the board for banishment ceases to exist immediately (Rule 186.1). With no object left to act on, the "its owner plays that unit back" instruction is ignored (Rule 359.3.e.6) — exactly the same result as Temporal Breach on a token (FAQ #12327). You can still choose a token as one of the units, but you've paid the Power for it and get nothing back.

For real unit cards it works normally: the card survives in banishment and gets replayed to the same location or its base — which does count as playing a unit, so "when you play a unit" and enter triggers fire again. Copying doesn't change anything: a Reflection token copying a real unit is still a token and still vanishes (Rule 185.1.a, FAQ #13043).

So Chronobreak is a reuse-your-real-units spell, not a token recycler — the only reason to banish a token with it is to clear your own token off the board, at full Power cost.