It is not "Vein popping sound". It is "(Shrill) crying", based on stylized font
"えーん" == "E---n"
It is not "Gloom". It is "(Drawn out) whining/crying", based on stylized font
I'd recommend, although a bit difficult, to learn the (Romanji)<->(Hiragana/Katanana) table by memorization.
This will allow you to learn "text" for onomatopoeia (to google meaning, or sound SFX out).
Otherwise it's image-based and hard to learn. Especially with stylized/graphical fonts emphasizing certain emotion.
bit after big that kid is getting a normal life with a good mother.
but i am saddened by the fact he never did try a birthday before now. i do hope that they find them.. and punish them.
anyway!
so adorable that they ask him what he wants for birthday.. so much love. 💝