Austrian High German is different from German High German is different from Swiss High German.
For example, Austrians refer to bread rolls as "Semmeln", while Germans call them "Brötchen". Austrians tend to avoid the Preterite in spoken language, while Germans use it pretty frequently etc etc.
"Ich holte mir eine Tüte Brötchen" vs "Ich habe mir ein Sackerl Semmeln geholt", for a practical example.
And yet we consider it the same language.
Source: Am Bavarian, we're officially nearly a fourth of Germany and the Austrians talk like we do ;)
More seriously, I couldn't tell you if anything about tenses is written (and differently) in Austrian school books, or if it's just the dialect creeping up.
What I can tell you that your example sounds kinda made up, although of course I know it's proper German.
Also, the M in BCMS is Montenegrin, the latest made-up language, not Macedonian (which is separate). Seems like not even the defenders of linguistic seperatism can keep up with the insanity ;-)
The Torlak dialect of Serbian is so transitional to Bulgarian/Macedonian that it could fairly be called a dialect of the latter. Even outside that dialect, it's not at all unusual to see Macedonians and Serbs in general converse, each person speaking his own language.
Similarly, the Croatian dialect spoken in the northwest of Croatia (which has become increasingly fashionable after independence) is transitional to Slovenian and there is greater mutual intelligibility than with standard Croatian.
Maybe, but it adds no argument to the issue of the same lang vs different langs. There's no clear purely linguistical distinction between dialect and language. As an old joke goes a language is a dialect with an army. In other words when it has a separate political status, and governed by a separate body - it's a language, no matter how similar it to other languages. The reason is that a literary/official language is defined by rules, and as rules are defined by separate entities, existing differences will be preserved, and new will emerge, and multiply eventually.
Sure, there's different dialects. But most languages that are old enough have those.