This is Twipsy (1999).
The main characters are a pair of human kids, Nick and Lissie Walker, and Twipsy, an odd-looking creature that lives in cyberspace and transports email data across the Internet. Twipsy has a black & orange head, a striped, multi-coloured body, and does vaguely look like something out of a cubist painting.
According to the broadcast history on the Wikipedia page, the show aired on RTP2 in Portugal.
On November 1, 1999, the animated series Twipsy aired on the German TV channel KI.KA with 52 short episodes, 13 minutes each (they were often paired to make 26 episodes, having a total length of 25 minutes per pair.) Seven months prior to the start of the EXPO 2000, the series premiere was used to get children accustomed to the upcoming World Exposition, however it focused only on character backstory, and had no connection to the Expo.
In the first episode, 13-year-old Nick was pulled by accident into Cyberspace. He then meets the colourful and feisty cybermessenger Twipsy, who introduces Nick to the virtual realm; of course Nick gets homesick and together, Twipsy sends him back to the real world, while inadvertently ending up there too.
A modified scanner is since being used as a Transporter into the universe of the internet. Through way, many other children, for example Nick's 8-year-old sister Lissie or his friend Albert experience many adventures and get to know the cyberspace realm, and most of the time, for Twipsy to get to know the aspects of the real world, such as weather, or his newfound love (and gluttony) of food.
The characters are displayed using computer graphics when they're residing in Cyberspace, and in the "real world" using conventional comic style. Apart from that, all people are nearly the same size and appearance as Twipsy himself.