You can change speechEvents.bin in audio folder with HEX (that's important!), swap like dc_rundown_pole_lec_01 & dc_rundown_pole_lec_02 with dc_rundown_pole_rai_01 and dc_rundown_pole_rai_02 - commentator will say about Leclerc instead of Raikkonen; also there is a way to replace the whole voices, by the speech_patch folder, Codemasters used it in F1 2015-2016, but you should know the folder name and the file name, for example you have speech archives in speech folder inside of the audio folder, to replace en_re_startup.nfs content, you have to create folders "speech_patch/en/engineer_startup/" and put audio files in .wem format there, but I dont know how to name folder instead of "engineer_startup" to replace other archives' content
also I know how to extract .nfs files so you can listen absolutely all voices from any codemasters game that uses .nfs archives for speech and I can give you an instruction to do both things (extract & replace by speech_patch folder) if you need
some facts:
1) Claire's voice files have something about F2, like "Davin will be close to you on the grid", or "How does it feel to see your old F2 rival moved to the top of the field in F1?" and they're all about someone with name Davin and Lucas, but there is noone named Davin or Lucas in the real F2, maybe they will add interviews in coop? (there are a lot of phrases with mark "f2" + 4 different variations of them)
2) Jeff's voice files have red flag in it, like "The race has been red-flagged, take care and bring the car back to grid." and also 4 different variations of it; + there was a subtitles for this red-flag speech, but codemasters removed them from .lng files just in f1 2018, its still exists in f1 2017 and maybe f1 2015-2016;
sorry for my bad english, hello from Russia