3#0.01, 2#0.5, 1#-10, -2#~

(([-+]?d+)#([-+]?d*.?d+|~))+

MISTAKE3#0.01, 2#0.5, 1#-10, -2#~AND_HERE_MISTAKE_TOO

(?<=^(?:[-+]?d+#(?:[-+]?d*.?d+|~),s)*)[-+]?d+#(?:[-+]?d*.?d+|~)(?=(?:,s[-+]?d+#(?:[-+]?d*.?d+|~))*$)

var block = @"[-+]?d+#(?:[-+]?d*.?d+|~)";   // Block/unit pattern
var pattern = $@"(?<=^(?:{block},s)*){block}(?=(?:,s{block})*$)";
var results1 = Regex.Matches("3#0.01, 2#0.5, 1#-10, -2#~", pattern)
    .Cast<Match>().Select(x => x.Value);
if (results1.Count() > 0)
    Console.WriteLine(string.Join(", ", results1));
var results2 = Regex.Matches("MISTAKE3#0.01, 2#0.5, 1#-10, -2#~AND_HERE_MISTAKE_TOO", pattern)
    .Cast<Match>().Select(x => x.Value);
if (results2.Count() > 0)
    Console.WriteLine(string.Join(", ", results2));

3#0.01, 2#0.5, 1#-10, -2#~