Unfortunatly the yeelight alexa skill supoports only the singapore server.
Most of the xiaomi philips products can not be connected to the singapore yeelight server at this time.
So all this very good products do not work with the alexa yeelight skill.
Is there a known planned timescale for the integration of this philips products to the singapore yeelight server?
It’s made by Philips, not Yeelight 
We definitely won’t support it.
Why should we support devices from our competitor? It’s unreasonable.
why they are sold under the xiaomi label? and the ceiling and tablee lights are supported by the mi home app?
That’s exactly what xiaomi ecosystem means. Products are made by different vendors, but follow the same protocol, so you can see all the products in MiHome app. However, all the work beyond MiHome app support are vendor-specific. All the services (Alexa/IFTTT/Google Home/Open API) provided by Yeelight are done by Yeelight team and has nothing to do with Philips.
If you are using Philips products and what some features, you should go to their forum and ask.
ok so yeelight and xiaomi are having different goals regarding the xiaomi ecosystem. yeelight is only supporting xiaomi yeelight prodicts. the mi home app is supporting all the products from different xiaomi vendors.
thats sad for the xiaomi costumers in europe 
but why is it possible to install the philips products in the yeelight app with the chinese server?
Are you sure?
I don’t that’s possible. Please send me a screen capture if you really could make it happen.
ok you re right. there only an issue that some philips products can only connect to the chinise sever.
Do you mean you can connect Philips products to Yeelight APP? Which product?
Show me a screen capture please.