The boards are designed for standard electrolytic since it is not in the audio path. They are affordable and do the job with no effect on sound. While you can use them in the audio path we typically avoid that.
That said tantalum caps are actually electrolytic. The thing about tantalum quirks that have been written about like exploding and catching fire, while unlikely in a pedal because of the limited power available from the power supplies if you use the wrong supply or install it backwards it could be a problem.
Therefore we suggest standard electrolytic but you could use either.
Also always socket transistors.