Anyone able to understand the problem of the testnet sync issue?
I haven't been able to grab a chance to find out.
I did take some time to process the Yandex tardumps into a git repos: https://github.com/datacoinproject/datacoin-core (08 is the last, I lost track during the flurry of Windows fixes). Might be worth using that as a base to explore testnet issues.
Also, having a in-wallet blockexplorer is a great idea -- the more blockexplorers the better I think -- I currently pay 100+ dollars a year to keep the cryptoID one going https://chainz.cryptoid.info/dtc/