Our timeline is not an ordered series of preconditions followed by inevitabilities. It does not hold that if some other civilization says "B", it must first have said "A" and follow by "C".

RF equipment is not built or designed by people working with or having understanding of quantum mechanics. Understanding waves could come from observing liquids, or if audio exists to them, that. Designing around noise can be done empirically as we do. Quantum mechanics in this area only matter due to our current chip manufacturing process, but who says they use semiconductors?

On the other hand they could also have a better understanding of light and photons and never build RF into their core technology stack, thereby not having people observe and analyze the hydrogen line.

The only strict order is that we know now that our previous theories were complete garbage, and we are still waiting to discover why our current theory is complete garbage.