There may indeed be no awards, but that can be hard to tell from the multi-city tool. Instead, just focus on one direction at a time. Also check plausible routings. Some partner metal does not show up online all the time, but I believe BR almost always does, which is the most common partner you might need.

There are a lot of threads on searching awards in the forum. In particular one that describes the ANA tool might be useful.

Actually,
I just searched and on the outbound ROC-TPE there's tons of availability in April in Y and C. The return is a little tougher. SYD-ROC seems to return no availability at all. Instead search SYD-SFO (or maybe some other intermediate point) and SFO-ROC.

There's not much (I haven't found any) saver availability on the direct SYD-SFO flight in any class, so you're going to have to do a lot of searching or connecting.