Arguably this confusion is meant to undermine the consumer choice of aircraft during the purchase. GOL has heavy competition from LATAM, AZUL and AVIANCA on most of their routes, and none of these companies are using the 737-MAX AFAIK.
If you have a preference to avoid this aircraft, you need to book flights on airlines that don't have any, or that are too long for it, or be prepared to abandon your ticket at boarding.
Did they? I still see a lot of references to the MAX 8 on their fleet page, notably separate from their 737-800 fleet.
Reference:
https://www.aeroin.net/gol-muda-nome-boeing-737-max-8-para-7...
The new name has hitherto been used only internally at Boeing and emerged when the company put out a statement on Wednesday to announce it had won its first order for the grounded 737 Max aircraft this year. "
Source: https://www.theguardian.com/business/2020/aug/20/boeing-737-...
And calling the variants -7/-8/-9 kinda makes sense (MAX 7/MAX 8/MAX 9 are more "official").
Also, I don't find your second paragraph arguable. The model numbers on these planes are not determined by lottery, or for fun. Their marketing departments agonize over every detail for months; they know exactly what they are doing.
Yes it should. This is airworthiness; this stuff has to work.
You don't give someone a pass on safety-critical stuff because "they usually do a good job". The company's past processes are irrelevant because it's their current corpus of airworthiness procedures that affects the continued airworthiness of their products that are still flying today. The company has demonstrated a serious problem and until it has demonstrated sufficient corrective actions taken to correct the problems observed then everything the company touches should be considered suspect. The fact that Boeing also made B-29s 70 years ago means exactly nothing except for PR purposes or to fanboys.
Boeing has no doubt made some changes, but I'll reserve judgment as to whether or not those changes are sufficient because I don't work for a Regulator and don't have the complete picture.