How should we interpret the cryptanalysis results of SIMON and SPECK?
Let's first get something out of the way. You say ".. key-recovery attack for SPECK32/64 ..". This is not true. The cryptanalysis you linked attacks SPECK32/64 with 10 rounds. This is less than half the amount of rounds used for SPECK32/64.

Then onto your actual question, is $2^{29}$ chosen plaintexts a good or a bad attack? I can't decide that for you, but I can give you an idea. SPECK32/64 uses a block size of 32 bits, or 4 bytes. This means that after encrypting 2.1 GB of plaintexts your key could be recovered. 

Whether that is deadly for security or not is up to you to decide, not me.