Overall the excavator is usable and of average quality.
One of the pivot pins on the boom-excavator link fell out during transport (or earlier), which was only discovered after the weird/whonky behaviour of the whole boom assembly during the first test operation.
The key issue was the lack of a manual that would specify operation, and more importantly a parts list, which would allow for local repairs in time to come w/o having to guess parameters, such as flow rates, pressures, rpms, etc.. Very few component manuals were eventually provided; after logging a complaint with Alibaba.
Computer-based translation may not always be accurate. This led to communication problems, leading to misunderstandings in what was asked for. It need to highlight that the sales person did their best to accommodate my queries, however, it seems that the manufacturing department was lacking urgency and or care.
My advice: add the requirement of an "industry best-practice manual" to the contract.