I would postulate a counterthesis that its not the language we speak that affects the way we think, but rather how much of that language we use and how much the (single) language is capable to express AND how much of different topics we read/hear (in that language). Just think of kids not so profound in their language - they think, they reason, but they can't argue about "to be or not to be...". But when they grow up, they more and more use and read other topics that utilize higher parts of the language, difficult sentences, etc.. -> so they LEARN and start to think differently on topics.

so, my postulation is:

the knowledge we gain shapes our thinking. Language itself is the transportation medium for the knowledge. Is the medium is small, so the knowledge described with the medium is also "small" or "not destinctive enough". We can use a "second" language then to make the knowledge more exact and mor destinct/tdefined.

But the knowledge can also be gained with other means - learning by doing, as exmaple. So, a language is not necessary to gain knowledge (numb and deaf and blind people also think, but are somehow limited in their expression ...)

so based on that, I postulate, it's a coincidence when a language shapes our thinking, but the cause and the "affecting part" is the real "knowledge-transfer" by the language. No matter if its sign language, pointing towards .. speaking piraha or russian or finnish-english.