The word Baile is the same in the nominative singular and genitive singular , Baile receives a séimhiú in the below sentence as the article aspirates masculine nouns in the genitive singular. Is that correct ?

Tá eolas an bhaile go maith aige,

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Bíonn rudaí maithe mall

Yep. Though I think I'd say "Tá eolas maith an bhaile aige." "Maith" is modifying "eolas" here, so the adjective form is more appropriate.

Redwolf

I think you might be arguing raw logic against a native turn of phrase there, Redwolf.

You could also think of it like the difference between "he knows the village very well" and "he has a good knowledge of the village", i.e., both would be correct.

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Múinteoir Gaeilge - Irish Teacher
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

Tá eolas maith ar an bhaile aige but Tá eolas an bhaile go maith aige
Tá Gaeilge líofa aige but Tá an Ghaeilge go líofa aige
Tá sláinte mhaith aige but Tá an tsláinte go maith aige

Thanks for those examples, Errigal.

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Múinteoir Gaeilge - Irish Teacher
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).