Ganesh Chaturthi missing in India

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Affected country

India

Affected public holiday

Ganesh Chaturthi

Source of the information

https://en.wikipedia.org/wiki/Ganesh_Chaturthi

More information

Additional source: https://en.wikipedia.org/wiki/Public_holidays_in_India

As stated in #282 support for the Tamil calendar and/or the Hindu calendar would make this way easier.

The holiday is on the 19th of September this year in India, see https://www.india.gov.in/calendar?date=2023-09
However, this may differ for for different territories.
According to https://en.wikipedia.org/wiki/Public_holidays_in_India and https://www.prokerala.com/festivals/ganesh-chaturthi.html it is known by different names in different parts of India and may not even be a holiday everywhere.

Also, as India has different calendars the exact date might differ too:
In general the holiday is on the 4th of the lunar month (thereby probably meaning the Hindu calendar, which would then be Bhadrapada at least this year) (according to [1], [2] and [3])
According to the Amanta tradition (see also the note in https://en.wikipedia.org/wiki/List_of_Hindu_festivals) and https://www.prokerala.com/general/calendar/hinducalendar.php?year=2080&mon=bhadra#next the 4th of the Hindu calendar in August/September this year (Bhadrapada 4, Anala) would indeed be the 19th of September 2023.

The date of Ganesh Chaturthi shall move between August and September (being 31st of August last year, 2022).
But according to https://en.wikipedia.org/wiki/Tamil_calendar the month that is mid-August to mid-September is Avani (known as Shrāvaṇa in Sanskrit).
If it's always around the 4th of Bhadrapada, why is Bhadrapada referred to as the equivalent of the Gregorian August-September in the Hindu calendar, but as the mid-September to mid-October equivalent in the Tamil Calendar?

How shall one understand this? Does the start of the month Avani move between mid-August and mid-September, then it should be more like the 4th of that month and wouldn't be the day it shall be this year, right? According to https://www.prokerala.com/general/calendar/tamilcalendar.php#previous Avani ends in September this year, shortly after Bhadrapada starts.
So do the equivalents in the Tamil Calendar refer to the end of the month, but the equivalents in the Hindu calendar refer to the start of the month? Are all the Wikipedia articles wrong?

According to https://en.wikipedia.org/wiki/Ganesh_Chaturthi in e.g. Tamil Nadu it shall be on the fourth day after the new moon in the month of Avani of the Tamil calendar and in Goa it shall be on the third of the month Bhadrapada. I don't know when the new moon in Avani is, but the 19th of September 2023 in the Tamil calendar will be according to https://www.prokerala.com/general/calendar/tamilcalendar.php?year=2023&mon=september&la=&sb=1#next the Purattaasi 3, Sobakrith in Tamil and the Bhadrapada 4, Anala in Shaka retrospectively, as the month of Aavani (Tamil) wil end on the 17th of September 2023.
But then again the government of Tamil Nadu states, that the 17th of September will be a holiday, but neither the 19th of September, nor the 20th of September.

In Mauritius, however, the holiday will be on the 20th of September (see here, here or here), which would not be the fourth of the month as far as I can tell, but also not the third of Bhadrapada.
But then again, https://npcs.govmu.org/SitePages/ViewAllPublicHolidays.aspx and https://cpb.govmu.org/SitePages/ViewAllPublicHolidays.aspx list the 19th as the public holiday instead of the 20th.

Please note: these Hindi / Sanskrit / whatever words may have various different spellings, due to the impossibility to translate them a 100% correct into English and my/others inability to read these languages.

[1] https://www.prokerala.com/festivals/ganesh-chaturthi.html
[2] https://web.archive.org/web/20171205043554/http://aglobalworld.com/holidays-around-the-world/mauritius-ganesh-chaturthi/
[3] https://web.archive.org/web/20120120005942/http://www.tourism-mauritius.mu/discover/festivals.html