Yeah, with |30.r21 first, White has options. I think 31.u18 works, and 31.s19 would work, also. R21 doesn't get to the right side on its own. Its purpose is to be downstream to j19, make that battle work, but it needs support to get to the right side. My theory, at first, was that s17 would be strong enough.
How about:
|30.s17? ... 31.q16 32.r21 33.o15 34.i21 35.k18 36.k20 37.l20 38.m21 39.t19 40.r19 41.t17 42.v19