Sorry I wasn't clear. I had "but"; I left it out of my post because it wasn't the part that seemed to be wrong. To be completely clear: "but I have to return" is correct; why isn't "but I need to return", besides being a more direct translation of "pero necesito regresar"?
Good question. "Tengo que" means "I have to." If an infinite comes after the phrase "tengo que", then only the infinite follows, so no "a" is needed before it. E.g. "tengo que caminar" = "I have to walk".
If the "a" was kept, the "a" would mean "to". So, the phrase "tengo que a regresar" would translate to "I need to to return." There are now two "to"s, which is unnecessary and repetitive.
However, if you are saying you are returning to a specific place, then "a + location" would follow the infinitive, e.g. "Tengo que regresar a Texas" means "I have to return to Texas."
Keep your tongue on your teeth when you say R. If R is the first or last letter it is sounded like RR which is the sound English speakers make when making fun of Scots. A single R in the middle is a single flap of the tongue. At first, English speakers try to make the sound like in English. Then when they manage to get it on the tip of their tongue, it rolls too much. That's an aspect of a Russian accent in Spanish. I ask English speakers to pronounce CATEDRAL with the T, D, R, and L on the teeth. Sometimes they get a funny look on their face when the R rolls for the first time in their life.
"And just why NOT?????" = "¿Y porrrrrrrr qué NO???????", so if you get it to roll, you can let it fly on that one.
That's an interesting question. I know there were a few generations who were taught the false grammar rule in English that you can't start a sentence with a conjunction, which is why you see However and Nevertheless used in the beginning of sentences a lot. But as coordinating adverbs, words like however require a semicolon between two clauses when the second begins with one of them. This pause concept makes however seem somewhat more consequential than but. But I have no real concept whether all these weight elements are the same in Spanish. Certainly changing from but to however is not going to change the meaning to any significant degree, but for the purposes of learning I think it is perhaps better to go with the conventional translation with but being pero and however being no obstante or sin embargo. I googled pero vs no obstante and got a hit from a chapter in a book. The chapter was entitled Contrastive Discourse Markers in Spanish. That certainly answers a lot more complex questions than yours from the perspective of Spanish, but ultimately your question is more about English.
Sure - if you have no desire to learn Spanish and hate doing the lessons. But if you'd like to progress a little further in an easier way, download the app on your smartphone. You can do a lesson in five minutes almost anywhere. There's no need to worry about grammar. Just listen, repeat, and understand what's being said. In a lot of the US, you'll get major points in Hispanic areas just for trying.
Thank you for your thoughtful comments. I agree that punctuation is required between a primary and secondary clause, but in the case of however I believe that it is more common to use a period rather than a semi-colon. However, I may be mistaken. You also reminded me of the strict translation in Spanish for however and, while I had learned them, I needed the reminder. As I stated in my original post, I expected my answer would not be accepted by DL. It was more an experiment to see, if it would be an acceptable translation. Again thank you.
No. Regresar and volver are interchangeable in this use. Volver is used in other ways as well, though. The DLE defines regresar using the words devolver and volver.
Spanish doesn't have point of view verbs like go back and come back or go in and come in. Those are from English's Germanic roots. Their words will be like the ones we have from French and Latin, return or enter. An other example would be present instead of to be here or to be there. Obviously these words can be good translations, but the point of view aspect (come vs go) has to be taken from the context.
Yes. I love Duo lingo, but I don't use the speaking exercises at all. You can turn them off in setting. In Spanish, French and German I don't need them anyway, but even in languages that I haven't had enough formal education in to know how to pronounce words I have decided they don't help, because I know they mark me wrong when I am right and right when I am wrong. But if you choose to do this, just remember to read all the Spanish outloud anyway because part of the problem is always just getting the flow of how the sounds, words and sentences flow.