Bongo Fury

I changed my brake fluid today. Here is what I did:

Used a syringe to remove as much old fluid from reservoir.
Replaced with new Dot 4.
Opened bleed on near side rear and let gravity do its work until I was happy fresh fluid was coming in.
Repeated on offside rear, near side front and offside front.
Throughout this, I topped up the reservoir with fresh fluid but at no point the brake pedal was pumped. Yes it took an age but seemed to be successful.

My question is whether there are any potential issues I may have caused?

No problems introduced but...
Opening the bleed nipples will change the fluid in the lines but it will not change the fluid sitting behind the caliper pistons. To do this you would need to clamp the flexy pipe open the bleed nipple and push the pistons back to their stops this will clear out the old fluid from the chamber so when you release the clamp and press your brake pedal fresh fluid will replace the old evacuted fluid. You may need to do this a couple of times.
Good luck.