In this paper, we study the semantics of a specification language for the coordination of concurrent systems, which supports time at different levels: various time domains, polychrony, and mixed metric/logical time constraints. The language itself is defined by a denotational semantics. In order to be able to construct the possible timelines for verification purposes, we also define a symbolic operational semantics, which is the reference for an efficient implementation of a tool for runtime-testing of heterogeneous systems. This study presents a novel way to link these two semantics by taking advantage of a coinductive unfolding principle of these timelines. Furthermore, these semantics and their equivalence have been formalized in the Isabelle/HOL proof assistant, together with proofs for soundness, completeness and progress.