Randomly present randomly selected subsets of elements from different groups

I have 1 idea using randomizer elements but I also have solid randomization procedures with JavaScript. If you share a minimally reproducible example of your survey in a .qsf (please do include the branch logic and the question blocks so I can see if there is a way to reduce that as well), I can have a go.

npetrov937, thanks for volunteering to help!
Here is my .qsf file. As you'll be able to see, what currently happens is that blocks appear in that order, for example:
G(roup)2.B(lock)1. / G2.B3. / G1.B2. / G1.B3.
It works as only 2 out of 3 blocks are selected per group BUT the blocks from specific groups are displayed one after the other. I would like it to appear like this, for example:
G2.B1. / G1.B2. / G2.B3. / G1.B3.
Please note that I simplified my survey A LOT. Otherwise, I have 144 blocks. That being said, I appreciate your help, but please don't spend too much time trying to figure a way to do this, especially if it's going to take a lot of copy-pasting of coding from my part. I was just curious to know if there was a way do to the randomization simply. If not, I have another way that satisfy me.
Reprex (1).qsf

Hello npetrov937,
I tried to use, in my survey, the code kindly made available here. However, for some reason, sometimes it does not work as I expected.
Here is the thing: I have a pool of 100 words (50 from "Group1" and 50 from "Group2"); each word is in a different block. From the pool of 100 words, I would like to randomly select 50 words - and only those would be presented to the participant: 25 from "Group1" and 25 from "Group2"; also presented in a random order.
Using the piece of code above, indeed 50 words are presented; however, sometimes, the survey displays 26 words from "Group1" and 24 from "Group2" (instead of 25 + 25 words).

Could you please help me trying to figure it out what might be going wrong? Thank you!
Here is the piece of code I am using:

Qualtrics.SurveyEngine.addOnload(function()
{
//function to get n random elements from an array
function getRandom(arr, n) {
var result = new Array(n),
len = arr.length,
taken = new Array(len);
if (n > len)
throw new RangeError("getRandom: more elements taken than available");
while (n--) {
var x = Math.floor(Math.random() * len);
result[n] = arr[x in taken ? taken[x] : x];
taken[x] = --len in taken ? taken[len] : len;
}
return result;
}

//defining the groups and the blocks for each group
blocks_dictionary = {
"Group1" : ["a1word", "a2word", "a3word", "a4word", "a5word", "a6word", "a7word", "a8word", "a9word", "a10word", "a11word", "a12word", "a13word", "a14word", "a15word", "a16word", "a17word", "a18word", "a19word", "a20word", "a21word", "a22word", "a23word", "a24word", "a25word", "a26word", "a27word", "a28word", "a29word", "a30word", "a31word", "a32word", "a33word", "a34word", "a35word", "a36word", "a37word", "a38word", "a39word", "a40word", "a41word", "a42word", "a43word", "a44word", "a45word", "a46word", "a47word", "a48word", "a49word", "a50word"],
"Group2" : ["b1word", "b2word", "b3word", "b4word", "b5word", "b6word", "b7word", "b8word", "b9word", "b10word", "b11word", "b12word", "b13word", "b14word", "b15word", "b16word", "b17word", "b18word", "b19word", "b20word", "b21word", "b22word", "b23word", "b24word", "b25word", "b26word", "b27word", "b28word", "b29word", "b30word", "b31word", "b32word", "b33word", "b34word", "b35word", "b36word", "b37word", "b38word", "b39word", "b40word", "b41word", "b42word", "b43word", "b44word", "b45word", "b46word", "b47word", "b48word", "b49word", "b50word"]
}


//creating an array for the current pp by going through each group's blocks and selecting 25 random blocks
current_PP_array = []
for (var group in blocks_dictionary) {
current_PP_array = current_PP_array.concat(getRandom(blocks_dictionary[group], 25))
}

Qualtrics.SurveyEngine.setEmbeddedData( "current_PP_blocks", current_PP_array)
this.clickNextButton()

});