You do not need to be sorry about your English, it is very good compared to my German!

Hundreds of channels (like 400 or so) is pretty common now here in Canada (and also the US). We may eliminate a few due to alternate language, etc. but once you have digital cable, satellite AND an OTA digital antenna, we tend to keep them there "just in case." (Add to that all the Internet Channels, and Netflix that are available but are not addressed by MCC.....) North Americans love their TV (and likely watch too much)!
WMC does have the ability to chunk them into TV Categories so that is a possibility for MCC to be able to group channels into smaller consumable numbers. Or I would ask you to consider a "paged" download, where you can set the number of channels to download at a time and then "page" through them. The standard on-screen Channel Guide, pages in groups of 10 or so, so that might be a good starting point because it's fast. If the user had the ability to page up or down in groups, or to directly enter a channel number as a starting point, that also helps get to a channel faster.
Congratulations on the most recent changes, by the way, you conquered the CH.x issue and that works flawlessly as far as I can tell. So MCC now recognizes and downloads data for channels like 2.1 and 2.2 etc. that are the norm here for Digital. I'm not certain if my debugging report will still be of any use to you?
I would make two more suggestions, and that would be 1) for a more intuitive way to "preview" Information on a channel (in the Android device) before actually changing the channel on WMC, what happens sometimes is if I'm not thinking I touch a channel thinking I am going to get more info on the program, but it switches to the channel. I forget now offhand whether you hold down the channel to get info - but a more explicit "I" button in the interface along with the program title to touch would be nice.
The second has to do with the time delay switching channels. Because you are "typing" the channel numbers, it works fine if you are already watching TV (i.e. it moves from channel to channel very smoothly). However if you were doing something else, like watching a Movie, OR the WMC is in "sleep" mode, then clicking a TV channel won't always get you to the channel as WMC seems to miss the channel input part (although it may switch to the Live TV mode, it just stays on the previously engaged channel because the tv channel change signal comes too quickly perhaps....). This is going to be one of those "lesser of two evils" kinds of options.
I hope this helps.
Thank you!
Wayne