Version 1.2.0 is released https://github.com/byteball/byteball/releases.
It includes ability to partially recover from seed:



As was said before, the seed doesn't allow to recover blackbytes because they are not stored on the public database.
Recovery works only in full wallets because it scans the local copy of the database for addresses generated from the seed.

To restore your bytes (but not blackbytes) from seed, you will need to download the wallet, choose "Full wallet", wait that it syncs and then go to the Recovery menu in Settings.

Also, a number of small bugs fixed in this release.