Ben Aaronovitch in an old pre-Lost Stories interview (paraphrasing) said if Earth Aid had happened, his planned TNG-pastiche opening would have been on a 1990 BBC budget and likely looked terrible, so maybe it was a good thing it didn't happen! So if fans are complaining the audios don't seem like the old 27 Up plans we built up in our heads, well, neither could the eps if they ever happened
(God knows what Night Thoughts would've been like, no way on God's green Earth is the BBC letting a story as gruesome as the audio out for the kids)
The Big Finish adaptations of these lost stories do give something of a feel for how the 27th series might have been. Not exactly the same of course - it’s a different medium after all. And the adaptations do take advantage of that by setting some of the action in Moscow, which would have been beyond the TV series at the time. It’s interesting that the adaptation of Ice Time into Thin Ice changed the ending of Ace going to Gallifrey, as their Gallifrey Time War box set shows her working there.
I do wonder whether the character of Lady Christina in Planet of the Dead was at least partly inspired by Kate Tellinger/Raine Creavey. A different background of course - the aristocratic Lady Christina was portrayed as being a cat burglar for the kicks rather than the more middle class professionalism of Kate/Raine.