and then another question we have so if we use the dashboard level filter in the custom URL params (for example,

{dash_attribute_filter_selection(label.tickets.market)}

, then when GoodData replaces the param with the actual value of the filter we get something like this in the custom URL it generates (after decoding the URL):

"IN[/gdc/md/msgsr4q760tfl6vbseji5tig22dcrhvh/obj/2538/elements?id=800]"

how do we turn the above into the actual text filter value that was used

This can be done via API or via our API wrapper "gray pages" as described here. If you need to check a single value really quickly, you can also copy-paste it into the Metric Editor.