It is not kufr to think that there are certain forbidden acts that may not draw any harm in this worldly life and that their punishment is delayed until the Hereafter. Allah ﷻ tells us in the Qur'an that He may defer His punishment until a specified time:
وَلَوْ يُؤَاخِذُ اللَّهُ النَّاسَ بِمَا كَسَبُوا مَا تَرَكَ عَلَىٰ ظَهْرِهَا مِن دَابَّةٍ وَلَٰكِن يُؤَخِّرُهُمْ إِلَىٰ أَجَلٍ مُّسَمًّى ۖ فَإِذَا جَاءَ أَجَلُهُمْ فَإِنَّ اللَّهَ كَانَ بِعِبَادِهِ بَصِيرًا
And if Allah were to impose blame on the people for what they have earned, He would not leave upon the earth any creature. But He defers them for a specified term. And when their time comes, then indeed Allah has ever been, of His servants, Seeing.
— Surat Fatir 35:45
If the sinners repent, He may forgive them as He wills, but if He were to impose punishment as sins occur, there would be no creature alive on this Earth. Another verse conveys a similar meaning in Surat Al-Kahf:
وَرَبُّكَ الْغَفُورُ ذُو الرَّحْمَةِ ۖ لَوْ يُؤَاخِذُهُم بِمَا كَسَبُوا لَعَجَّلَ لَهُمُ الْعَذَابَ ۚ بَل لَّهُم مَّوْعِدٌ لَّن يَجِدُوا مِن دُونِهِ مَوْئِلًا
And your Lord is the Forgiving, full of mercy. If He were to impose blame upon them for what they earned, He would have hastened for them the punishment. Rather, for them is an appointment from which they will never find an escape.
— Surat Al-Kahf 18:58
Moreover, to think that certain impermissible acts bring harm as punishment is not entirely accurate as it is not conclusive. The harm may indeed be a form of harm, and it may also be a form of cleansing or a form of test of the faith of a person.
Allah ﷻ may, at His own will, bring forth our punishment to this world so that we have no punishable sins on Judgment Day as the Prophet ﷺ said in the following hadith:
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا اللَّيْثُ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ، عَنْ سَعْدِ بْنِ سِنَانٍ، عَنْ أَنَسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم: إِذَا أَرَادَ اللَّهُ بِعَبْدِهِ الْخَيْرَ عَجَّلَ لَهُ الْعُقُوبَةَ فِي الدُّنْيَا وَإِذَا أَرَادَ اللَّهُ بِعَبْدِهِ الشَّرَّ أَمْسَكَ عَنْهُ بِذَنْبِهِ حَتَّى يُوَفَّى بِهِ يَوْمَ الْقِيَامَة.
Anas narrated that the Messenger of Allah (ﷺ) said: "When Allah wants good for his slave, He hastens his punishment in the world. And when He wants bad for His slave, He withholds his sins from him until he appears before Him on the Day of Judgement."
— Jami' at-Tirmidhi, Book 36, Hadith 94
There are certain sins that may not be expiated through a worldly punishment, and certain other sins that mandate punishment in both worlds. However, I am not sure where you read that consumption of alcohol is one of the sins that its punishment is expedited to this worldly life. There is a hadith by the Prophet ﷺ that lists two sins (oppression and severing family ties) in a non-conclusive form as resulting in punishment in this world in addition to what is stored for such sinners on Judgment Day:
عن أبي بكرة قال قال رسول الله صلى الله عليه وسلم: مَا مِنْ ذَنْبٍ أَجْدَرُ أَنْ يُعَجِّلَ اللَّهُ تَعَالَى لِصَاحِبِهِ الْعُقُوبَةَ فِي الدُّنْيَا - مَعَ مَا يَدَّخِرُ لَهُ فِي الآخِرَةِ - مِثْلُ الْبَغْىِ وَقَطِيعَةِ الرَّحِمِ
Narrated Abu Bakrah: The Prophet (ﷺ) said: "There is no sin more fitted to have punishment meted out by Allah to its perpetrator in advance in this world along with what He stores up for him in the next world than oppression and severing ties of relationship."
— Sunan Abi Dawud, Book 43, Hadith 130
The hadith was graded as sahīh (authentic) by Muḥammad Nāṣiruddīn al-Albāni in his book Silsilat al-Aḥādīth aṣ-Ṣaḥīḥa 3/588, where he also added another narration of a similar hadith that Aṭ-Ṭabarāni that added lying and treason to the list. Based on these two hadiths, one can conclude that the following sins will have both worldly punishments as well as punishment in the Hereafter for those who do not repent:
- Severance of family ties
While knowing that the Prophet ﷺ did not list them using conclusive language and that there may be other sins that will draw punishment in both worlds, there is nothing that can affirm that drinking alcohol is one of such sins. There is also nothing that affirms that uttering words of kufr is only punishable in the Hereafter.
While it is better for a believer to have one's sins cleansed in this worldly life, this is not a matter that one should ask Allah for. It should be entrusted entirely to Allah's will, and to keep one's supplication to grant us good in this world and in the Hereafter, and to save us from Hellfire as the hadith of the Prophet ﷺ says:
حَدَّثَنَا أَبُو الْخَطَّابِ، زِيَادُ بْنُ يَحْيَى الْحَسَّانِيُّ حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي عَدِيٍّ، عَنْ حُمَيْدٍ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم عَادَ رَجُلاً مِنَ الْمُسْلِمِينَ قَدْ خَفَتَ فَصَارَ مِثْلَ الْفَرْخِ فَقَالَ لَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم: هَلْ كُنْتَ تَدْعُو بِشَىْءٍ أَوْ تَسْأَلُهُ إِيَّاهُ. قَالَ نَعَمْ كُنْتُ أَقُولُ اللَّهُمَّ مَا كُنْتَ مُعَاقِبِي بِهِ فِي الآخِرَةِ فَعَجِّلْهُ لِي فِي الدُّنْيَا. فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم: سُبْحَانَ اللَّهِ لاَ تُطِيقُهُ - أَوْ لاَ تَسْتَطِيعُهُ - أَفَلاَ قُلْتَ اللَّهُمَّ آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الآخِرَةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ ". قَالَ فَدَعَا اللَّهَ لَهُ فَشَفَاهُ.
Anas reported that Allah's Messenger (ﷺ) visited a person from amongst the Muslims in order to inquire (about his health) who had grown feeble like the chicken. Allah's Messenger (ﷺ) said: Did you supplicate for anything or beg of Him about that? He said: Yes. I used to utter (these words): Impose punishment upon me earlier in this world, what Thou art going to impose upon me in the Hereafter. Thereupon Allah's Messenger (ﷺ) said: Hallowed be Allah, you have neither the power nor forbearance to take upon yourself (the burden of His Punishment). Why did you not say this: O Allah, grant us good in the world and good in the Hereafter, and save us from the torment of Fire. He (the Holy Prophet) made this supplication (for him) and he was all right.
— Sahih Muslim, Book 48, Hadith 31