Your variant still depends of new line. I mean it doesn't work properly with 
{name_b param_v="wh"}{name_a param_x="abc" param_a="fsd" param_y="def"
+}
{name_z param_sd="zka" param_s="df"}{name_a param_y="wtf" param_z="kro
+" param_ch="www"}

[download]
But thanks anyway. When I parsed your regexp I found new for me \K and totally understood how \G works. See below my solution based on your. Seems it works properly. 
s/
(?:\{name_a | \G)
[^{}]+?
\K
\w++(?<!param_[xy])
="[^"]+"
//xg;

[download]

In reply to Re^4: RegExp: pos management in global substitution by OlegG
in thread RegExp: pos management in global substitution by OlegG

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