Making precise tempo changes in playback

Wanting to make playback do fermatas, I know how to use the draw tool to reduce the tempo temporarily. But then I want to restore it to the previous value. The draw tool seems very crude and an inaccurate way to go. I cant easily get exactly the previous setting, even if I look at the very tiny tempo value in the upper left corner. What’s the more accurate way to do this?

And why do the tempi in the signposts show different decimal places from the value you think (sorry it that’s not clear…)?

What I do is to edit the restoring tempo in Write mode, using the properties panel or double clicking (in that case, you have to hide the metronome mark in the properties panel again).