With its Platform segment booming, Roku has announced the launch of its new operating system, Roku OS 10.5, which is set to start rolling out across devices in the coming weeks. Meanwhile, two new 4K Streaming Sticks are a misjudged attempt to lift a flat Player segment, and we are unsure whether they are the offerings needed to boost international expansion. First, the software. Roku OS 10.5 promises improvements to the UI and UX on both mobile and first screens, with more opportunities for content recommendations, smooth access to instant watching and a host of neat audio-centric capabilities. 10.5 puts the spotlight on live and ad-supported content. The new UI offers a Live TV channel button directly onto the home…