Well written Trouble report, thank you!
The commands you are using is correct. However you'll need to specify yet another switch.
What happens is the software tries to guess which is the font you want to change by looking at the highest occurrence. This works most of the time, but there are a few LRF out there that don't follow this pattern.
What you have to do is run this command
lrf2lrf -e Silverberg-Live-Again.lrs
This will produce a report with the Text and font size
The output looks something like this
LRS written to .a.lrs.tmp
TextStyle ObjId=52 Fontsize = 100
Recommend PageStyle = 56
Found PageStyle = 56 Occurrence = 2
Found PageStyle = 54 Occurrence = 2
Recommend TextStyle = 52
Found TextStyle = 52 Occurrence = 2
In my example there was only one font used but you'll have more. In the example you'll see I spit out the TextStyle, ObjID, and fontsize. (They are underlined above)
Find the correct Object ID and pass that value using the '-x' switch
lrf2lrf -x 52 -s 80 -t 0 -b 0 -l 0 -r 0 -o NewLrfFile OldLrfFile
Note do not use "52" use the object ID listed when you run the '-e' command. From your trouble report it should be 72,75, or 80.