What are the limits for CTL and ATL values?

Hi all,
.
I training by GoldenCheetah. My weight is 72kg.
I setting CP20=240
.
Now my result are
CTL=102
ATL=118
(Look attach file : TSS per day)
.
If I adjust CP20 from 240 to 250
TSS per day will decrease, resulting in ATL and CTL will also decrease.
It affects the TSS value per week.
.
What are the limits for CTL and ATL values?
Should I adjust CP20?
.
*note : When I train by workouts course
I will adjust target watts if at any section they are too easy or too difficult.

I don’t want to make FTP test

Thank you for the answer.