Thank you; however, when I search Budapest-Kelenföld to destination of Bratislava hlavna on the site on the site you mention I do not see those times (instead I see departures for 7:47 am, 9:02 am, etc.) and it says there will be 1 transfer, which I am trying to avoid. Even more strange, the transfer is at Budapest-Nyugati (which should be closed then?)
If I do a general Budapest to destination of Bratislava hlavna search, I do see a 8:28 departure 10:54 arrival, if that was the one were referring to? But once again, the departure is from Budapest-Nyugati. I am showing that it is 0 transfers, but I'm not sure that is correct because of the other link you provided showing the temporary buses. Additionally, like mentioned before isn't Budapest-Nyugati closed?
When I search departure from Budapest-Keleti, I get similar results as from Kelenfold time-wise (7:53 am, 9:05 am), and also with the same transfer at Budapest-Nyugati.
All these are showing for me as $10-$11 euros in price (at least before fees if there are any) and the trains leaving from Nyugati are 130 BÁTHORY EUROCITY or 278 METROPOLITAN EUROCITY.
Needless to say, I am still very confused! Considered taking Flixbus instead but it's a bit longer and my luggage doesn't fit their policy.