How to modify an Exported Result/Strategy Tcl script for a design update?

Background:

After exporting the strategy of an InTime result to a Tcl script, you re-use the Tcl script for an updated design. The Tcl script gives good results but additionally, you want to adjust some compilation parameters after placement in order to meet timing.

Scenario (Vivado example):

The original project is a post-synthesis netlist (I. e. an opt_design DCP)
InTime found a good floorplan result, and you exported the result to a Tcl script.
There are changes to the RTL, and you use the Tcl script to re-run the same floorplan. The floorplan still gives a good result, but has a few timing violations.
You want to adjust the parameters of post-placement steps to try to resolve the remaining timing violations.
Since placement takes a long time to run, you want to save time by starting from a post-place netlist.

Steps:

Here is the relevant portion of the original Tcl script.
Lines 12 and 13 specify the input netlist.
Lines 25 to 32 apply the floorplan.
Modify the Tcl script.
Add a command to write a post-place netlist (see line 37).
Run the Tcl script in the FPGA vendor tool to create the post-placement netlist.
Modify the Tcl script again.
Specify the post-placement netlist as the input.
Comment out commands that are related to placement.
Adjust post-placement compilation settings or add new compilation steps.
Run the Tcl script in the FPGA vendor tool.