That won't be easy finding the strings of the games own Career.
Customs Careers comes with their own packages and finding the strings is a lot easier to do. The strings of the base game own Political Career are muffled under one huge STBL in the fullbuild0.package within the games install directory,
here's a copy</a> which you are able to edit in <a class="wiki_link" href="/Packer">Packer or whatever source you tried it with the tutorials.
The hard part will be finding the strings attached to the Political Career in between all the other strings that came with all sort of things from the Base Game that needs Languages.
Follow these steps:
1. DL
Packer and DL the file that contains the STBL (look on top)
2. Unpack both
3. Open the STBL BaseGame.package in Packer
4. You will see the languages of all the game provides, select yours you wish to have (on which language the game is installed, all others you can delete if you wish too making the file smaller in size).
5. Right Click the line and export it to a *.txt file, close packer for now
6. Open the *.txt file in notepad or any text editor, preferably <a class="wiki_link_ext" href="
https://notepad-plus-plus.org/" rel="nofollow">Notepad ++</a> (its an enhanced version of Windows application of Notepad)
7. Now press CTRL+F and find the names you wish to change, since its the careers lvl names, here is a list of the names in English, if you are using another language then you will have to research it what they are:
<ul class="quotelist"><li>Lvl 01; PodiumPolisher</li><li>Lvl 02; BallotCounter</li><li>Lvl 03; Campaign Intern</li><li>Lvl 04; Yes-Man</li><li>Lvl 05; City Council Member</li><li>Lvl 06; Local Representative</li><li>Lvl 07; Mayor</li><li>Lvl 08; Governor</li><li>Lvl 09; Vice President</li><li>lvl 10; Leader Of The FreeWorld</li></ul>8. Edit them to whatever you desire them to be
9. When you are done with the *.txt document, save it.
10. Back to Packer open the STBL Basegame.package, select your language and right click it and select import
11. Navigate to your *.txt file and press open (you will see on the right side the location where its imported from
12. Save Package in Packer and put the STBL BaseGame.package inside your Mods\Packages folder
13. Delete your Caches, run your game and check the Career
In your first Turn you might not get all the notices of whatever pops up when you play that Career, but you can write them down or make a screenshot whenever such pop up can be related to that career and then find it in the STBL and change it to your taste that fits your way of play.
Again, don't forget the delete all other Languages in the package you don't use. As a whole its 29,4MB large and might consume more resources than needed since your game can only handle one language.
Hope this helps and good luck