Having spent an hour with Bing AI telling him/her that certain M Code functions didn't exist, I took a breather and came back to it with a more basic outline of my requirement. Ironically, the solution was much simpler than I thought.
I added some dummy data to the Input Table (blue). The 'Sequence' column in the Output Table (green) shows the count of winning/losing streaks.
Simply paste your data into the 'Input' Table (blue). Select the Output Table (green), right-click your mouse and select 'Refresh'.
You may need to adjust data you have as I use BF results, which denotes winners as 1 and losers as 0. e.g. if you have W or L, then replace the text accordingly.
*caveat; not fully tested
