fsharp-dotnet, 192 bytes

Result

AC

Duration

7228ms

Code [DL]

let f=stdin.ReadLine
let w=string>>stdout.WriteLine
let T=f()
let t=T.IndexOf"T"
w T
let mutable i=f()
while i.IndexOf"K"<0 do w T;i<-f()
let k=i.IndexOf"K"
w(i.[..k]+String.replicate(t-k)"K")

stdin

                                  T               
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
       K                                          

stdout

                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
                                  T               
       KKKKKKKKKKKKKKKKKKKKKKKKKKKK

stderr

The template "Console Application" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on /tmp/Proj/Proj.fsproj...
  Restoring packages for /tmp/Proj/Proj.fsproj...
  Generating MSBuild file /tmp/Proj/obj/Proj.fsproj.nuget.g.props.
  Generating MSBuild file /tmp/Proj/obj/Proj.fsproj.nuget.g.targets.
  Restore completed in 207.54 ms for /tmp/Proj/Proj.fsproj.

Restore succeeded.

strace