Hi!
To change the trackpad buttons you will need to replace the entire palmrest section of your laptop - otherwise you risk damaging the trackpad which you don’t want.
Lenovo has a guide (you have to follow it until page 88 (94 in the PDF) - don’t worry, most of that is legal stuff): https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/t430_t430i_hmm_en_0b48304_04.pdf
A new part can be found [https://www.aliexpress.com/item/New-Original-for-Lenovo-Thinkpad-T430-T430I-Palmrest-KB-Cover-Keyboard-Bezel-Upper-Case-with-Fingerprint/32766408865.html?spm=2114.search0104.3.101.664853bd9LRoOz&ws_ab_test=searchweb0_0,searchweb201602_3_10320_10065_10068_318_10547_319_10546_317_10548_10696_450_10084_10083_10618_452_535_534_10304_533_10307_10820_532_204_10843_10059_10884_10887_100031_320_10103_448_449,searchweb201603_2,ppcSwitch_0&algo_expid=f80b3fe3-ea81-4434-82bc-af9b30b69f4e-14&algo_pvid=f80b3fe3-ea81-4434-82bc-af9b30b69f4e&priceBeautifyAB=0|here].