Kirsch

Kirsch or Kirschwasser, an unsweetened eau de vie distilled from cherries, and it is often called Cherry Brandy too, but it is not to be confused with Cherry Liqueur which too is often called Cherry Brandy, for that is a sweetened liqueur with a brandy base.

You can't use Kirsch and Cherry Liqueur interchangeably since the liqueur is sweet and Kirsch is not.

Gin

Gin is a distilled alcoholic beverage that has it's origin in medicinal liquor made by monks and alchemists across Europe. The historical Gin producing regions are Southern France, Flanders and Netherlands. Gin was originally created to provide aqua vitae from grape and grain distillates.

During the Middle ages, the newly found substance Ethanol was considered by Alchemists to be the water of life, and an aqueous solution of ethanol was in use all over Europe and had different names and is literally the origin of many spirits like Whisky ( from the Gaelic uisce beatha for water of life ). Today Gin is produces from a wide range of ingredients, which gave rise to numerous distinct styles and brands. The predominant flavour of Gin is from the Juniper berries and then each different distillery flavours it further with an assortment of botanicas or herbs, spices, floral and fruit flavours, in different combinations. Gin is commonly drank mixed with Tonic water but it is also often used as a base spirit for many gin based flavoured liqueurs like Sloe Gin.

Pineapple Juice

Rich in antioxidants, this juice pressed from the pulp of the Pineapple is a good protection against cell degeneration, It contains bromelain, a group of enzymes known to reduce inflammation, improve digestion and boost immunity. In drink mixing, there is nothing like the tropical flavour of pineapple juice to add that tropical freshness and nuance to a cocktail.

In drink mixing pineapple having a fruity tropical aroma pineapple juice is a good companion for tropical fruits such as mango, banana, passion fruit, and also pairs well with oranges and grapefruit juice.

Pineapple juice is the juice pressed out of the pulp of the pineapple fruit, several varieties of pineapple are used to manufacture commercial pineapple juice. High on Vitamin C and enzymes that have been shown to activate healthy immune response, it’s a good juice to start a day. The enzyme bromelain in pineapple juice, triggers analgesic response in the body to fight pain and reduce swelling. In cocktails, Pineapple juice goes best with Vodka and is often a regular juice in many Vodka cocktails.

White Curacao

Curaçao is a liqueur flavored with the dried peel of the bitter orange laraha. It's been a popular liqueur for more than 150 years, the Dutch East India Company created this orange liqueurs by steeping orange peels in alcohol from the island of Curaçao and called it Curaçao liquor, unlike Triple Sec, Curacao has added spices and herbs to the orange and Curaçao comes in a variety of colours such as clear, orange or blue.

Blue Curaçao being the most used of them, in cocktails. Although Curacao is an orange tinted liquor, Blue Curacao is a regular Curacao dyed bright blue to give it a striking appearance, and thus is a very popular cocktail mixer, whenever a striking colour is desired.

Blue Curacao is usually around 25% ABV.

Blue Curacao is essentially Orange Liqueur tinted Blue, the colour doesn't influence the taste and thus Orange Curacao is interchangeable with Blue Curacao in recipes, if the colour is not important in the appearance.

NOTE: Blue Curacao being an Orange Flavoured Blue Liqueur, it's primary purpose in a cocktail is introducing the Orange flavour and the striking sky blue to the drink, so, if a bottle of Blue Curacao liqueur is something you are not planning to buy right now, you can manage with the Blue Curacao Syrup.
It would add the same flavour and colour profile to the cocktail, all we need to do is simply count for the alcohol absent in the syrup and account for it.