You are right – “there is no word for brother in Aramaic.” – Likewise in Genesis we see Abraham is his (Lot) uncle because Scripture’s reveals this by looking at more Scripture as you showed – And in Mary’s case, the word brother is also meant because of the usage of sisters in Matthew 13:55-56.
As far as John having Mary move in – No problem – Jesus’ brothers were not saved yet as Scripture also tells us in John 7:5 – for neither did his brethren believe in him.
Your church uses “presumes” and “assumes” to fool the ignorant, whereas those that are in the Word, know the Word so much better that we have peace. Mary is blessed, Scripture tells us this. No where does it say that she would be a meditor for us to Jesus and She said “DO as Jesus tells us” (John) but that was it, never mentioning that she would become an intercessor for us. Is God hard of hearing or what? No, so why assume that when Isaiah 8:19 tells us not to contact the dead on behalf of the living?