Is this actually true, though, when jumping between programming paradigms?
Do you mean learning or mastering a language. It is kind of different. Looking for "ideomatic python" will help getting pythonic Python code done.
Not going against the spirit of the language helps.
For example, many years ago, before I really got functional programming, I tried to learn ML and while I figured the syntax out very quickly, solving problems in a functional style was a lot more difficult and I found it hard to use the language. Learning to use Python or Ruby or Java or C#, albeit not idiomatically, is a hell of a lot easier.
Of course, knowing a language is a lot more than just learning enough to use it, though you certainly don't have to master a language to know it (and many people will never completely master their languages, despite knowing them quite well and using them effectively - for example, I'd wager few people have truly mastered C++).
"Programming language is just a syntax, the core logic of getting things done is already available in your brain."
Here is what i'd do
A) Remember what you already learnt from your favorite language
B) Once you get a hang of basic syntax, start with Examples and keep making progress.C) Pick a simple task, from what you have already solved before. Program it in the new language by expanding your skills towards 2-5 points and you are done !