Hi Ivo
Gelcrem and corn starch are two different products.
Gelcream is a modified potato starch and its activity is to texturize like a cream or thickener (whatever you want to say), you can do it cold or hot.
It is a modified potato starch that is used as a thickening and texturizing agent in foods. Due to its ability to create a creamy texture, it is often used in food products such as sauces, dressings, soups and desserts.
It can be used hot and cold, which makes it useful for preparations in which a smooth, lump-free texture is desired. It can also be used as a substitute for other starches in existing recipes to achieve a smoother, more uniform texture.
On the other hand, corn starch is a carbohydrate composed of two polysaccharides, amylopectin and amylose. Also known as cornstarch or cornstarch, it is a fine, white powder, without aroma or flavor, it is immiscible in cold water, but soluble in hot water.
In this case you could replace the Gelcrem with cornstarch but you will have to cook the preparation so that it can cook and take on texture. You should try and see if the result is what you are looking for.
Greetings.