Unconventional key generation. I didn't go through this code, but I couldn't help but notice that bitcore-mnemonic is a Java applet. As far as I know web-browser and Java based seed generators won't provide the same entropy that a python or C++ seed generator can. Again, to my admittedly limited knowledge this is due to whether the applet can access the CPU's ability to generate randomness, and I don't know if this particular Java app can do so. If I'm wrong in this instance, this could be a non-issue.
Depends. Those CSPRNG generally will still seed their randomness pool with the entropy from OS's CSPRNG and under normal circumstances, this wouldn't be compromised. From what I can tell, they are calling the correct functions. CPU is just one of the many inputs for the entropy pool and there are various other sources for entropy, hardware interrupts, noise, keyboard inputs, etc. The randomness falls on the OS's ability to gather these, not the CPU.