@Zooquest You will hear clicks because there will be jumps between samples.... if the playback was at a sample level of 0 and you change the delay time to a point where the level is 1 then the click will be loud.
You will hear "steps" as the playback point is probably being changed repeatedly by the ctrl messages.
You could experiment with a [lop~] filter in the delayed sound output, with a high value e.g... [lop~ 5000] but you will lose some high frequencies in the echo.
That might sound natural though, like an old tape echo, but you will probably still hear the clicks a little.
Or you could "duck" the echoes by not changing the delay time immediately, reducing the echo volume to zero in say 3msecs using using [vline~] and not bringing the echo volume back up to 1 (in, say, 3msecs again) until you have NOT received a ctrl message to change the delay time...... for again 3msecs.
The last part of that would need a [delay 3] using the property that any new bang arriving at its inlet will cancel the previously scheduled bang.
You would need to duck the FB signal as well though, and all that that might sound worse than the [lop~].
I cannot remember well...... but this "sampler_1.pd" might contain elements useful to demonstrate "ducking" https://forum.pdpatchrepo.info/topic/13641/best-way-to-avoid-clicks-tabread4/12
Or do a crossfade between separate delays once the incoming control messages have stopped..... https://forum.pdpatchrepo.info/topic/12357/smooth-delay-line-change-without-artifacts ..... as you can then avoid the "duck"ing effect.