Thanks for the update! I checked the changes.
This items are resolved
1 - The Playing (‘Afspelen’) tag now changes depending on the player state 
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2 - Homey now updates the speaker widget/tags when I use an external controller and the technical message is now gone .
3 - Album art now update, though some time directly after updating to the new app version, the album art stayed empty. Seems to have resolved itself .
6 - When switching to the TV input, the Track tag now shows ‘TV/HDMI’ . I think this is fine, though my Playbar uses an optical input (the TV-part applies in my case). I think the newer soundbars use HDMI. Further, some Sonos devices have a traditional line in (jack). Not sure how switching to that input is displayed (I cannot test that, as I do no have a device with such an input).
These items may need some further attention
4 - This now always shows a fixed label ‘Radio’ in the Track tag and the station name in the Artist tag, when playing a radio station sourced by TuneIn. However I expect it to dynamically display the online service name, if available/provided (like ‘Sonos Radio’). Also, the track and artist info is not shown. Further, when I use Sonos Radio as a service (instead of TuneIn), this ‘Radio’ label is not shown, instead the actual artist and track info is shown. So this does not seem to work consistently 
. Also see below my remark on the Album, Artist, Track tags.
5 - The Track / Artist / Album tags and album art are cleared now , but I noted that the Position and Length tags are not .
7 - In my case the Length tag sometimes keeps the value of the prior song and is not cleared when switching to e.g. an online radio station (that, I assume, does not provide length info). I haven’t figured out yet in which cases this tag is cleared and when not .
Analysis of Album, Artist, Track tags used in Homey and the official Sonos integration
There are three main tags available for displaying music info: Album, Artist and Track. These are also the ones Homey uses to populate the speaker widget. This works fine for local music, that have exactly there three tags.
However when steaming music from an online service (in my case radio stations), there are actually two more pieces of information: the name of the online service and the radio station name. Since there are only three tags available, the additional info is put into or combined with the other information in the three main tags (Album, Artist and Track).
I am not sure if it is the Sonos API that decides how this extra information is included in the three main tags, or it is a design choice by Athom in the official Sonos app. I assume it’s a combination. Regardless, it seems to be applied consistently depending on the scenario.
I made the following overview that shows the scenarios and how the three main tags are populated in the official Sonos app (based on my observations):
Looking at the image, the first two groups of sources (local music and physical input) are already covered by your app. The last group (online service) are handled differently sometimes in your app. Also see my earlier remark on item 4.
Ideally I would like your app to mimic the behavior of the official app, which results in all available info being displayed by combining it - when necessary - in the available tags. But I can imagine that you have also your own thoughts on this matter. Whichever option: it would be nice if also the name of the online service and radio station name are included somehow in the available tags in a consistent manner, without losing the album/artist/track info.
. Some additional observations regarding the Shuffle and Repeat function.
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