EDIT: I just realized that this keyboard has a USB/digital audio recording feature built in, which my older PSR-E433 does not have. Everything I typed below relates to the keyboard's built-in 6 track sequencer, and NOT the USB/digital audio recording feature. I have never used the USB/digital audio recording feature of the newer keyboards, so I do not know how they work and whether or not it is possible to record a total live performance with the right and left hand sides of the keyboard.
If I understand you correctly, you are trying to record right-hand strings and left-hand chords to the keyboard's built-in sequencer/recorder. And, it sounds like you are trying to record the actual left hand chords that you are playing manually, without using the auto-accompaniment. Unfortunately, this is not possible. The sequencer tracks 1 through 5 will only record the right-hand side of the keyboard when using a split voice (though it will record both the main and dual voices, if you are using the dual voice). These tracks cannot record the left side of a split keyboard. The separate A (accompaniment) track is used for recording an auto accompaniment, and that will record the chords you're playing, but it will play them using the pre-programmed instruments and patterns of whatever style you have selected, and not with the split voice of the left-hand side of the keyboard. And, these chords have to be recorded separately (as a separate track) and cannot be recorded at the same time you are playing a right-hand melody.
You can turn off different elements of the style, such as the bass part or the pad part, and I usually turn off everything except the drums and just use the A track to record my drum background when doing a multi-track recording with the sequencer/recorder.
With that said, not that long ago, I learned that, when playing the keyboard live (not recording to the sequencer) and using the auto-accompaniment and style, you CAN combine the style's pre-programmed patterns with the split voice, so that you would also hear the chords you're playing with the split voice, along with the pre-programmed style pattern. But, I suspect that this feature cannot be recorded to the A track -- however, I've never tried it. In any case, this left-hand part has to be recorded separately to the A track when recording to the built-in sequencer/recorder and cannot be recorded all at once while playing the right-hand part, as if you were playing the song live.
To record yourself playing both sides of the keyboard live, you'd want to hook the keyboard to a computer and record the audio to a digital audio workstation (DAW), which is just a program you'd load on your computer that is designed to record audio, digitally, through the computer's USB port. I use a free program called Audacity, which is great in my opinion, but there are plenty of other programs, as well.
As for the spongy buttons, this keyboard does use a kind of rubber for the buttons, so maybe that's what you're feeling? However, they should still push with a noticeable tactile click (though not a very hard click). Since the E463 is a current model, if you have any music store nearby (not just the one where you bought your keyboard), I'd call and see if they have an E463 on display, then go there to see if the new one has a similar feel to the buttons. While some often-used buttons may wear a little more than the others, it would be odd for all of the buttons to be worn out at once.
