Map challenges is bronze and higher?

Question

I was just playing Mass Effect 3 Multiplayer, on the map Firebase Reactor Silver. Halfway I got a notification that I was on 75% completion on the challenge Firebase Reaction silver waves. However, a few waves later, I received the challenge of the same map, but on bronze. Is it expected behaviour that challenges like waves completed are not like stated on the N7HQ:

Firebase Reactor: Bronze Waves

Complete 100 Waves on Firebase Reactor: Bronze

but rather like:

Firebase Reactor: Bronze Waves

Complete 100 Waves on Firebase Reactor: Bronze or higher

Answer 1

Yes.

Completing map challenges for a difficulty also completes them for lower difficulties. So by earning progress towards Firebase Reactor: Silver Waves, you are also earning progress towards Firebase Reactor: Bronze Waves. Likewise, doing waves on gold will grant you credit towards silver and bronze. This also applies to bronze/silver/gold/platinum extractions for Squad Elite.

Adding your wording of "or higher" would make the challenge requirements more clear, but people doing silver are expected to be able to finish bronze anyway.