The article is talking about Budh/Budha - बुध - which is the word for the planet Mercury. The word for Wednesday comes from this बुध just as the other days of the week are named after the classical planets, the sun and the moon.
The word Buddha-बुद्ध meaning 'enlightened' which is where 'Buddhism' is derived from, is unrelated.
Why sometimes showing in the middle of the assigned lesson no listening lessons, what happens, those are not highlighting, can't move next one, unable to complete the lesson, also I completed all lessons in Hindi language, reached check point 4, but not shown anything whether course is completed successfully or not, repeated lessons are practicing, next level learning Hindi language how to go please inform me.... Thank you K Appala Ramesh....
You have completed all the lessons in the Hindi tree to the highest level. बधाई हो (Congrats)!! There should be a golden owl at the end of your tree to indicate completion.
The tree will be updated at some point in the near future with all new lessons but until then, might I suggest doing the reverse tree (English course for Hindi speakers)? A lot of learners find that helpful.