What is the ruling on someone who pronounces the letters of the first Taslimah incorrectly by mistake, and does the Imam bear that on his behalf?

You may be afflicted with waswas (whispers/obsessive thoughts); so, stay away from them and do not pay attention to them. If you made a mistake in the taslim (definition) that prevents its validity, then repeat it to be absolved from the prayer. It is sunnah (definition) for you to perform the prostration of forgetfulness (sujud (definition) al-sahw) if you are an Imam, praying alone, or a follower. If you made a mistake in the first taslim and then performed the second correctly, your prayer is valid because, according to the majority of scholars, only one taslim is obligatory. If you doubt your mistake in the taslim, do not pay attention to the doubt.