kotlin, 237 bytes

Result

AC

Duration

5582ms

Code [DL]

fun main(){var s = readLine()!!
println(s)
val r=Regex("T")
val p=r.find(s)!!.range.start;for (m in generateSequence(::readLine)){val q=m.toCharArray()
q[p]='r'
println(Regex("K.*r").replace(String(q), {z->"r".repeat(z.value.length)}))}}

stdin

                T                                 
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
  K                                               

stdout

                T                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
                r                                 
  rrrrrrrrrrrrrrr                                 

stderr

OpenJDK 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.intellij.openapi.util.JDOMUtil$2 to constructor com.sun.xml.internal.stream.XMLInputFactoryImpl()
WARNING: Please consider reporting this to the maintainers of com.intellij.openapi.util.JDOMUtil$2
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

strace