Working correctly with your solution.
I'm also doing this with the text in de LinearGauge

I will try this later.

I also found a problem for the linear gauge. It looks like it doesn't save the Bottom Axis Title (at least: after compiling it stil says 'Axis Title %') and on the other moment it is even changed back to this in designer mode.

I'm using version TeeChart Pro v2012.06.120613 32bit VCL.
Create like this:
Add TChart -> Add Series: gauges: 'Numeric Gauge' -> then open the gauge.
Tab 'Format' -> there tab 'Back' -> there tab 'Gradient' and there I create a different Gradient.

Left is compiled, right is designer.

I have a question about TCharts Numeric Gauge.
No matter what theme or pallete I choose, after compiling and running the program, the gradient on the back is always returned to his standard 'green'-white gradient.
The GUI designer in delphi does show the gradient correctly.