On a small update note an early usage of this track was spotted on a off-air recording on the same SBT network probably in 1987 or older (SBT was founded in 1981):
Curiously this clip is announcing a Speedy Gonzales cartoon, another fictional Mexican character. If this was intentional choice it may indicate that the source has a Mexican or Latin American theme. Or the tune was repurposed from the Speedy Gonzales association to the Chespirito's shows on the network.
The research sadly still has no strong lead, we know nothing beyond the usage of the track. Everything is just guessing work.
By now I have a huge collection of library music and this tune isn't there. Also I cannot find examples of other vintage library music used in Brazilian TV. No Italian, French, German labels or obscure releases were ever used by TV stations here.
The library music connection to SBT network comes from some tunes from KPM, Bruton and Valentino used in programming specially children's and comedy. I believe that this is indeed a library track it made its way to Brazil first through American distribution then unofficially imported.