oblmov
The passages that you describe as "worthless philosophical ramblings" are part of Tarski's results. He could not have left them out without obscuring the meaning of his proofs. Possibly model theory would not exist today had he done so. It would certainly have taken longer to develop.
Another instructive example is Per Martin-Lof's lectures On the Meanings of the Logical Constants and the Justifications of the Logical Laws: https://www.ae-info.org/attach/User/Martin-L%c3%b6f_Per/Othe.... Unlike Tarski's paper, this contains no formal proofs whatsoever; if the sentence you quote is worthless, then I imagine "There is no evidence outside our actual or possible experience of it. The notion of evidence is by its very nature subject related, relative to the knowing subject, that is, in Kantian terminology." is worse than worthless. Nevertheless these lectures have been of great importance in logic and computer science. You can see some of their impact in the citations here: https://scholar.google.com/scholar?cites=2483744927635326348
You may be unable to find any useful meaning in this kind of writing, but most mathematicians do not share your difficulty. This is fortunate, since the field would be greatly impoverished if it purged itself of all philosophy and philosophy-adjacent work. I would normally encourage you to read https://terrytao.wordpress.com/career-advice/theres-more-to-... on the role of non-rigorous big picture thinking in mathematics, but it deals entirely with human understanding of mathematics and is therefore only of interest to Terence Tao and other such pseudoscientists.
I'm not clear on whether you think The Concept of Truth in Formalized Languages falls into the "actually just mathematics" category or the "making up random equations" category. If the latter, I assure you that Tarski's proofs are sound. Here's a simple explanation of the most famous result from the paper in case you found the original proof inaccessible: https://qubd.github.io/files/TarskiUndefinability.pdf. A more general discussion of Tarski's work and other axiomatic theories of truth can be found at the Stanford Encyclopedia of Mathematics: https://plato.stanford.edu/entries/truth-axiomatic/
Here's a paper by Tarski, widely cited by both mathematicians and philosophers and containing both formal and informal reasoning: http://www.thatmarcusfamily.org/philosophy/Course_Websites/R... I don't know how one could "remove the philosophy" from this work without making it far less useful to mathematicians. The entire reason the T-schema is used in model theory is because of Tarski's philosophical argument that it provides a meaningful definition of truth.