You wrote: . . . also when printed on color paper the text become transparent for some reason (Showing the paper color through the stroke), even though the text was made white and the PDF document shows white text.
You can't print white using an inkjet or laser printer because there isn't white ink or toner in your printer.
The white needed to come from your paper which should be white.
All printers and presses use CMYK inks or toner.
What is the definition of White? C=0, M=0, Y = 0, K=0 so not a single droplet of any ink is being placed on the paper in any area that is supposed to be white..
Of course the color of the paper will show in areas where there is no ink.
When you see something white that is printed on a dark paper it using a special spot color Opaque White on a offset press..
(there is a single inket model from Epson that can print an ink that appears to be white. The model is $7,000 by the way. the [white] ink is $350, all the other inks are only $90)
From the Epson website:
Epson UltraChrome HDR White Ink introduces an all-new Organic Hollow Resin Particle Technology, which forces light to randomly scatter, producing the illusion of seeing the color white.
Notice that even Epson only claims it produces the illusion of white.
The only way around this issue is to print on White paper and print the "color of the paper" everywhere else on the paper that doesn't have your design elements.