Is the word entendia the same in Brazilian and European Portuguese?

No

While the spelling and grammar of "entendia" are identical in both dialects, there are differences in typical usage and pronunciation.

In Brazil, "entender" is the standard, most common verb used for the act of comprehension (to understand). In Portugal, while "entender" is used, the word "perceber" is much more natural and frequent when expressing the idea of comprehension. In Portugal, "entender" is more specifically used for the act of interpreting something or forming an opinion (e.g., "to interpret as"). Additionally, the pronunciation differs: Brazilian Portuguese tends to have more open, melodic vowels, whereas Continental Portuguese features more closed, reduced vowels.

Brazilian Portuguese Usage

• Eu não entendia nada do que ele dizia. (I didn't understand anything he was saying.)
• Ela entendia muito de matemática quando era criança. (She understood a lot about math when she was a child.)
• Ninguém entendia o motivo daquela confusão. (No one understood the reason for that confusion.)
• Eu entendia o seu ponto de vista, mas não concordava. (I understood your point of view, but I didn't agree.)
• Antigamente, as pessoas entendiam menos sobre tecnologia. (In the past, people understood less about technology.)

Continental Portuguese Usage

• Eu não percebia nada do que ele dizia. (I didn't understand anything he was saying.)
• Ela percebia muito de matemática quando era criança. (She understood a lot about math when she was a child.)
• Ninguém percebia o motivo daquela confusão. (No one understood the reason for that confusion.)
• Eu percebia o teu ponto de vista, mas não concordava. (I understood your point of view, but I didn't agree.)
• Antigamente, as pessoas percebiam menos sobre tecnologia. (In the past, people understood less about technology.)