Just a different view of mine, since the two sliders have exactly the same structure, even when the first slider does not completely fade away before another one approaching, it is still easier for players to read the pattern when they are stacked. Because players already perceived how the upcoming slider would look like, where it starts and ends.
Not to mention the bpm of this song is so slow (which gives you more than enough time to see the first one fading and second one coming), this pattern can still apply to much higher bpm maps imo, assumed that the rhythm suggests so.
But in anyway, making the two sliders overlap certainly is not the solution imo. If the slider really "doesn't fade away fast enough for us to see the slider path clearly", then overlapping makes it even harder to read the path, because, well... it's overlapping.