SED-POSIX-specified -E option inside script - bash

Question

I have a tricky question.
I have this .sed script where I need to do some stuff and then execute all the lines of the script with "sed -f script.sed filename.csv"
Inside the script I have used a regexp expression and if when executing the script I use -E, the script works. (sed -E -f script.sed filename.csv)
BUT, the thing is, I CANNOT used it, so in the terminal I need to execute the script like this "sed -f script.sed filename.csv"
Then, the question is, Is there a human possible way to make a regexp expression WORK inside a SCRIPT without using -E in the terminal? Can it be included INSIDE the SCRIPT somehow?
I will write down the script to give more context:
s/ESP/Spain/g #this line changes ESP for Spain in all rows
s/DEN/Denmark/g #this line changes DEN for Denmark in all rows
s/NED/Netherlands/g #this line changes NED for Netherlands in all rows
s/^([^,]*,)([^,]+)((,[^,]*){5},(shooting|judo),)/\1\U\2\L\3/ #This line, changes to UPPER CASE all names of athletes that have as sport either judo or shooting. This is the line that does not work without the -E in the terminal.
/[0],[0],[0],$/d #This line deletes all rows where the last 3 columns have these values
1 c id,name,nationality,sex,date_of_birth,height,weight,sport,gold,silver,bronze,info #this line makes the header not upper case
If you need some data to work with, there you have it:
id,name,nationality,sex,date_of_birth,height,weight,sport,gold,silver,bronze,info
388896171,Abdelraouf Benguit,ALG,male,1985-07-03,1.83,90,judo,0,0,0,
285603057,Abderrahmane Mansouri,ALG,male,1995-01-13,1.72,66,cycling,0,0,0,
545134894,Abderrahmane Meziane,ALG,male,1994-03-07,1.68,62,football,0,0,0,
969824503,Abdullah Alrashidi,IOA,male,1963-08-21,1.83,84,shooting,0,0,1,
897549624,Abdullah Hel Baki,BAN,male,1989-08-01,,,shooting,0,0,0,
153457,Abdullahi Shehu,NGR,male,1993-03-12,1.70,,football,0,0,1,
This is part of a file named athletesv2.csv
Please don't ask why I can't use it, but I'm forbiden from using this option.
BR,

Answer 1

You can use the first three commands as is:
s/ESP/Spain/g #this line changes ESP for Spain in all rows
s/DEN/Denmark/g #this line changes DEN for Denmark in all rows
s/NED/Netherlands/g #this line changes NED for Netherlands in all rows
The fourth command should be "converted" to POSIX BRE:
s/^\([^,]*,\)\([^,]\+\)\(\(,[^,]*\)\{5\},\(shooting\|judo\),\)/\1\U\2\L\3/
Note that this syntax is only supported by GNU sed (the \| as an alternation operator and \+ as one or more quantifier are GNU extensions).