I noticed that the official BOM for C1 and C27 for the Mouser part points to an NP capacitor specified to 25V, whereas the BOM explicitly states >35V. So, can this part be used or should the BOM be updated?
Also, for C14, C25, C33 there seems to be a part available at Reichelt that is only 7mm tall: SM 100/16RAD.
Boy, where did you get that sunburn? That’s scary!
The Reichelt part is good, as is the Mouser part. I guess I should be more blunt when suggesting the update (or bluntly speaking: the correction) of information :-).
To answer your initial Question:
The Voltage Rating for Caps is the maximum safe Voltage the Cap will deliver its estimated Lifespan. Since the Ambika only uses ± 8V a rating of 35V or 25V is either fine (in fact both will live as long as the Material allows), even 16V is twice as much as needed.