So.... I have this same issue much of the time.   And...there is NO way to "select all" for the entire envelope and nudge it up or down with the Qwerty?  Seems I have accidentally "highlighted" an entire envelope, but that was by mistake and I moved on.... maybe it was an illusion or faulty memory???

And yes...aren't there track volume envelopes?   Isn't that what happens when your "write/read" the track??  I do that a lot I want to think, then go back with the pencil and fix, as I'm playing back.  THEN, I'd like to make OVERALL adjustments (total gain up/down as the mix progresses), like it appears the OP wants to do as well.
 

mixmkr
So.... I have this same issue much of the time.   And...there is NO way to "select all" for the entire envelope and nudge it up or down with the Qwerty?  Seems I have accidentally "highlighted" an entire envelope, but that was by mistake and I moved on.... maybe it was an illusion or faulty memory???

There is actually a way to select an entire envelope, and adjust its volume, I use this feature all the time.
 
With Automation Lanes open, left mouse click in the blank space just to the left of the "R" automation read button.
This selects the entire automation envelope including all the nodes. Then you can hover the Smart Tool above the automation envelope . . . an icon with up + down arrows appears, and lets you drag the entire automation envelope of that track up or down.
 
It's tricky, but you can also select multiple tracks automation envelopes, and adjust them all at once. using this method.

thx noynekker...  great tip.
 
after trying that...
I ALSO found that using the smart tools (these things are great), you can select any portion of the envelope first, then switch to the "+" and move the selected envelope portion up or down.  That's REALLY handy!  I'm going to wear this feature out for sure.

I wanted to make an update to this.
 
I have been using the Sony Volume plug now for about six months.
 
I have found this to work out very well. Many times I needed to change the overall volume of a track that had automation, and what a relief to find that I had automated a plug's volume instead of the track volume. The volume and gain sliders on the track remain available, and the relative volume/gain automation stays in place.
 
No bad side effects so far.
 
FYI.