If I say plan instead of intend my answer is rejected. To me they mean the exact same thing in this context, only I would only ever say intend in a formal setting.
One can intend to do something without (and typically before) planning on how to do it.
Planning how to do something is not the same as planning on doing aomething, at least in standard American parlance. Planning to swim is synonymous with intending to swim, or meaning to swim.
I see “planning on swimming” as synonymous with “intending to swim”, and “planning to swim” as synonymous with “preparing to swim” (or “planning how to swim”).
I see the distinction. But I do think most people would use "I plan to swim today" and "I plan on swimming today" more or less interchangeably.
Can you please explain why it is intends to swim and not intends swimming?
Do they swim a lot in Ireland? Is the beach popular? Are swimming pools?
Yes, believe it or not, people who are otherwise quite sane plunge into the Atlantic and swim
Seriously Mike? Which of the teanglann pronunciations do you think was recorded by an American?
If I met you and your brother, do you think I'd be able to tell you apart based on the minor differences in the sound of your voices, even though you were both brought up in the same household? It's perfectly normal for different people to have minor differences in their pronunciation, and even for a single individual to pronounce the same word differently in different contexts.
The pronunciation of faoi dhó in this exercise is quite close to the Connacht example on teanglann, certainly well within the normal variation that you would expect, particularly given that the teanglann example is pronounced as a standalone phrase, whereas the the exercise has a following word, which can make a slight difference (It's hard to imagine either the Munster or Ulster examples sounding quite like that in an actual sentence).