Shenzhen CoolKit Technology Co., Ltd → eWeLink
It seemed to me to be common knowledge. eWeLink makes software, that is, if I understand correctly, the entire ecosystem, such as applications and web versions. Presumably, they are also responsible for the entire aspect of the servers to which Sonoff devices connect.
Shenzhen Sonoff Technologies Co., Ltd → Sonoff
Team designs and sends the designs to the factory (subcontractor?). This team creates firmware for Sonoff products as an integral part of the device.
ITEAD Studio → Sonoff, Nextion, AIRSPY…
Whether they are owned by the same person or separate ones… I don’t know, China again and half of the property is in the hands of the government. Apparently both teams work in one building, I think.
Founder of ITEAD Studio | SONOFF | eWeLink → @Alexie ???
https://twitter.com/freezingxie
This forum has probably always been perceived as the official one for Sonoff/eWeLink. The fact that statistically the eWeLink team is definitely more active here does not mean that sometimes someone from Sonoff will not comment here once a year. 
And where to report problems… God himself is not sure. Official communication channels, via applications or forms, or here, but this forum has never had much traffic and we have to be very lucky for our problem to be noticed, let alone solved.
@Daniel_Zhan Your team needs to be more active on the forum, I guess…