"It seems to me that this is necessary to structure politics better in the United Kingdom, to take into account the progress achieved by devolution and to learn lessons for the future of the United Kingdom as a whole."
I'd dispute that word "progress", but...
"Those questions concern the UK as a whole and we would do better to create a body with a UK wide remit to consider constitutional questions for the constituent nations and regions of the United Kingdom."
...yes, I agree 100%.
The Devolution Experiment has affected all parts of the UK, its "progress" therefore needs to be analysed on an all-UK basis- for example, an interesting question to be thinking about, how has the "progress achieved by devolution" impacted on the biggest part of the Kingdom, England?